U.S. patent number RE40,643 [Application Number 11/318,391] was granted by the patent office on 2009-02-24 for rotary hammer.
This patent grant is currently assigned to Black & Decker Inc.. Invention is credited to Michael Stirm.
United States Patent |
RE40,643 |
Stirm |
February 24, 2009 |
**Please see images for:
( Certificate of Correction ) ** |
Rotary hammer
Abstract
A rotary hammer includes a spindle 18 which can be rotatably
driven by an intermediate shaft 24 by way of a drive device. A tool
holder 16 is arranged for rotation with the spindle 18, and for
releasably holding a bit or tool for selective rotation and/or
reciprocation. A pneumatic hammering arrangement facilitates
repeated impacting of the bit or tool for reciprocation within the
tool holder (16). A mode change mechanism includes a knob 18 for
selectively operating the rotary hammer in any of three modes,
identified as a rotary drive only mode, a hammer only mode and a
rotary hammer mode.
Inventors: |
Stirm; Michael (Oberursel,
DE) |
Assignee: |
Black & Decker Inc.
(Mewark, DE)
|
Family
ID: |
9889344 |
Appl.
No.: |
11/318,391 |
Filed: |
December 23, 2005 |
Related U.S. Patent Documents
|
|
|
|
|
|
|
Application
Number |
Filing Date |
Patent Number |
Issue Date |
|
Reissue of: |
09826841 |
Apr 6, 2001 |
06666284 |
Dec 23, 2003 |
|
|
Foreign Application Priority Data
|
|
|
|
|
Apr 7, 2000 [GB] |
|
|
0008465.7 |
|
Current U.S.
Class: |
173/48;
173/104 |
Current CPC
Class: |
B25D
16/00 (20130101); B25D 16/006 (20130101); B25D
2211/061 (20130101) |
Current International
Class: |
B25D
11/00 (20060101) |
Field of
Search: |
;173/48,104,109,128,200,201,210,212,216 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
|
|
|
|
|
|
|
3 322 963 |
|
Jan 1985 |
|
DE |
|
0 775 555 |
|
May 1987 |
|
EP |
|
0 589 337 |
|
Mar 1994 |
|
EP |
|
Primary Examiner: Rada; Rinaldi I.
Assistant Examiner: Chukwurah; Nathaniel
Attorney, Agent or Firm: Markow; Scott B. Ayala; Adan
Parent Case Text
.Iadd.CROSS-REFERENCE TO RELATED APPLICATION
This application is a Reissue of U.S. Pat. No. 6,666,284 B2, issued
Dec. 23, 2003, which claims priority to Great Britain application
Serial No. 0008465, filed Apr. 17, 2000. .Iaddend.
Claims
What is claimed is:
1. A rotary hammer, which comprises: an intermediate shaft (24)
which is rotatably driven by a motor of the rotary hammer when
power is supplied to the motor; a spindle (18) which can be driven
in rotation about its axis by the intermediate shaft 24 through a
spindle drive arrangement (62,64); a tool holder (16) arranged for
rotation with the spindle (18) for releasably holding a bit or a
tool such that the bit or tool can reciprocate; a pneumatic
hammering arrangement (20,21,22) located within the spindle (18)
which can repeatedly impact the bit or tool held within the tool
holder (16); said pneumatic hammering arrangement comprising a
piston (20) which can be reciprocally driven by a hammer drive
arrangement (34,36,38,39,40,42) which can translate rotary drive
from the intermediate shaft (24) to a reciprocating drive to the
piston (20); and a mode change mechanism for changing the operation
of the rotary hammer to operate in any of three modes, a rotary
drive only mode, a hammer only mode or a rotary hammer mode; said
mode change mechanism comprising: a single actuator (8) switchable
by a user of the rotary hammer amongst the three modes of
operation; a spindle driving member (56) rotatable on the
intermediate shaft (24) for driving the spindle drive arrangement
(62,64); a hammer driving sleeve (34) rotatable on the intermediate
shaft (24) for driving the hammer drive arrangement
(34,36,38,39,40,42); and a mode change sleeve (52) which is
permanently driven by .Iadd.the intermediate shaft (24)
.Iaddend.and shiftable along the intermediate shaft (24) .Iadd.to
change the operation of the rotary hammer to operate in any of the
three modes.Iaddend.; where, upon the switching of the actuator (8)
by a user, shifts the mode change sleeve (52) along the
intermediate shaft (24) amongst the three modes positions, such
that in a first rotary drive only position the mode change sleeve
(52) transmits rotary drive to the spindle driving member (56) to
transmit rotary drive to the spindle drive arrangement (62,64), in
a second hammer only position the mode change sleeve (52) transmits
rotary drive to the hammer driving sleeve (34) to transmit rotary
drive to the hammer drive arrangement (34,36,38,39,40,42), and in a
third rotary hammer position the mode change sleeve (52) transmits
rotary drive to the spindle driving member (56) and to the hammer
driving sleeve (34) to transmit rotary drive to the spindle drive
arrangement (62,64) and to the hammer drive arrangement
(34,36,38,39,40,42).
2. The rotary hammer according to claim 1, which further comprises:
a driven member (54) on the mode change sleeve (52); a driving
member (50) mounted non-rotatably on the intermediate shaft (24) in
permanent engagement with the driven member (54), so that rotation
of the intermediate shaft rotatably drives the mode change
sleeve.
3. The rotary hammer according to claim 1, which further comprises:
a driving member (54) on the mode change sleeve (52); a driven
member (48) on the hammer drive sleeve (34); and wherein the hammer
drive sleeve (34) is located towards the rear of the mode change
sleeve (52) and the driven member (48) is engageable with the drive
member (54) to transmit rotary drive from the intermediate shaft
(24) to the hammer drive sleeve (34).
4. The rotary hammer according to claim 3, wherein a driven member
(54) on the mode change sleeve (52) which engages a driving member
(50) on the intermediate shaft (24) is axially extended to form the
driving member (54) of the mode change sleeve (52) which is
engageable with the driven member (48) on the hammer drive sleeve
(34).
5. The rotary hammer according to claim 1, which further comprises:
a driven member (58) on the spindle drive member (56); a driving
member (54) on the mode change sleeve (52); and wherein the spindle
drive member (56) is located towards the front of the mode change
sleeve (52) and the driven member (58) is engageable with the
driving member (54) to transmit rotary drive from the intermediate
shaft (24) to the spindle drive member (56).
6. The rotary hammer according to claim 5, wherein a driven member
(54) of the mode change sleeve (52) which engages a driving member
(50) of the intermediate shaft (24) is axially extended to form the
driving member (54) which is engageable with the driven member (58)
on the spindle drive sleeve (56).
7. The rotary hammer according to claim 1, which further comprises:
a driven member (48) on the hammer drive sleeve (34); a driving
member (54) on the mode change sleeve (52); a driven member (58) on
the spindle drive member (56); the hammer drive sleeve (34) is
located towards the rear of the mode change sleeve (52) and the
driven member is engageable with the driving member (54) to
transmit rotary drive from the intermediate shaft (24) to the
hammer drive sleeve (34); the spindle drive member (56) is located
towards the front of the mode change sleeve (52) and the driven
member (58) is engageable with the driving member (54) to transmit
rotary drive from the intermediate shaft (24) to the spindle drive
member (56); and the mode change mechanism is arranged such that in
a first rotary drive only position the mode change sleeve (52) is
shifted to a forward position on the intermediate shaft (24) to
transmit rotary drive to spindle driving member (56) through the
driving member (54) and the driven member 58, in a second hammer
only position the mode change sleeve (52) is shifted to a rearward
position on the intermediate shaft (24) to transmit rotary drive to
the hammer driving sleeve (34) through the driving member (54) and
the driven member (48), and in a third rotary hammer position the
mode change sleeve (52) is shifted to an intermediate position on
the intermediate shaft (24) between the forward and rearward
positions and transmits rotary drive to the spindle driving member
(56) through the driving member (54) and the driven member (58) and
transmits rotary drive to the hammer driving sleeve (34) through
the driving member (54) and the driven member (48).
8. The rotary hammer according to claim 1, which further comprises:
a mode changing member (68); and wherein the switching of the
single actuator (8) shifts the mode change sleeve (52) through the
mode change member (68).
9. The rotary hammer according to claim 8, which further comprises:
a housing part (2,4); and the mode change member (68) is mounted on
the housing part (2,4) of the rotary hammer so as to be slideable
in a direction substantially parallel to the intermediate shaft
(24).
10. The rotary hammer according to claim 8, which further
comprises: a mode change arm (72) on the mode change member (68);
and wherein the mode change arm (72) extends laterally of the mode
change member (68) with the arm (72) surrounding at least a part of
the mode change sleeve (52) and is connected to the mode change
sleeve (52) such that shifting of the mode change member (68)
shifts the mode change sleeve (52) through the mode change arm (72)
amongst the three mode positions.
11. The rotary hammer according to claim 8, which further
comprises: a housing part (2,4); a rotatable knob (8) forms the
actuator (8) and is mounted on the housing part (2,4); an eccentric
pin (14) on the rotatable knob (8); and wherein when the rotatable
knob (8) is rotated the eccentric pin (14) is rotated and slideably
engages with the mode change member (68) in order to shift the mode
change member (68) to shift the mode change sleeve (52) amongst its
three positions.
12. The rotary hammer according to claim 1, which further
comprises: a biasing arrangement (76,78) which is located between
the actuator 8 and the mode change sleeve (52) in order to bias the
mode change sleeve (52) towards the position on the intermediate
shaft (24) which corresponds to the position to which the actuator
(8) is switched.
13. The rotary hammer according to claim 1, which further
comprises: a mode change member (68); a mode change arm (72) on the
mode change member (68); a biasing arrangement (76,78), which
comprises: a first spring member (76); and a second spring member
(78); wherein the mode change arm (72) extends laterally of the
mode change member (68) and at least partly surrounds a part of the
mode change sleeve (52) and is connected to the mode change sleeve
(52) such that shifting of the mode change member (68) shifts the
mode change sleeve (52) through the mode change arm (72) amongst
its three positions; the biasing arrangement (76,78) located
between the actuator (8) and the mode change sleeve (52) in order
to bias the mode change sleeve (52) towards the position on the
intermediate shaft (24) which corresponds to the position to which
the actuator (8) is switched; and the first spring member (76)
located between a forward end of the mode change sleeve (52) and a
forward facing part of the mode change arm (72) and the second
spring member (78) located between a rearward end of the mode
change sleeve (52) and a rearward facing part of the mode change
arm (72).
14. The rotary hammer according to claim 1, which further
comprises; a spindle lock (70) to lock the spindle (18) against
rotation when the rotary hammer is in a hammer only mode.
15. The rotary hammer according to claim 14, which further
comprises: a mode change member (68); the spindle lock (70)
comprising: a first locking member (70); and a second locking
member (62,64); and wherein the switching of the single actuator
(8) shifts the mode change sleeve (52) through the mode change
member (68) and the first locking member (70) is located on the
mode change member (68) and engages the second locking member
(62,64) located on the spindle (18) when the mode change member
(68) is shifted to a hammer only mode position to lock the spindle
(18) against rotation.
16. The rotary hammer according to claim 1, which further
comprises: the pneumatic hammering arrangement comprising: a ram
(21); a reciprocally driven piston (20) which is reciprocally
drives the ram (21) through a closed air cushion; and an anvil (22)
which is repeatedly impacted by the ram (21) and, in turn, impacts
the bit or tool held in the tool holder (16).
17. The rotary hammer according to claim 1, wherein the
intermediate shaft (24) is substantially parallel to the spindle
(18).
18. The rotary hammer according to claim 1, wherein: the spindle
drive member (56) comprises: a driving member (60); a driven member
(62), which forms a part of the spindle drive arrangement (62,64);
and wherein the driving member (60) is in permanent engagement with
the drive member (62).
19. The rotary hammer according to claim 1, wherein the hammer
drive arrangement is a wobble plate arrangement (36,38,39,40).
20. The rotary hammer according to claim 1, which further
comprises: a releasable detent arrangement (90,92,94) for
releasably latching the actuator (8) in a mode switch position.
.Iadd.21. The rotary hammer according to claim 1, wherein the mode
change sleeve is a single sleeve. .Iaddend.
.Iadd.22. A rotary hammer comprising: a housing; a tool holder
coupled to the housing and configured to releasably hold a tool; a
spindle configured to rotate about a first longitudinal axis of the
spindle to cause drilling motion of a tool held within the tool
holder; a piston that reciprocates within the spindle along the
first longitudinal axis to cause hammering motion of a tool held
within the tool holder; a motor at least partially disposed in the
housing; an intermediate shaft configured to be rotated about a
second longitudinal axis by the motor when power is supplied to the
motor; a spindle drive mechanism coupled to at least one of the
intermediate shaft and the spindle to selectively transmit rotary
motion of the intermediate shaft to rotary motion of the spindle; a
piston drive mechanism coupled to at least one of the intermediate
shaft and the piston to selectively transmit rotary motion of the
intermediate shaft to reciprocal motion of the piston; a mode
change mechanism configured to select among a drilling mode, a
hammering and drilling mode, and a hammering mode, the mode change
mechanism including a front sleeve portion and a rear sleeve
portion each shiftable along the intermediate shaft and permanently
driven by the intermediate shaft to change the operation of the
rotary hammer to operate in any of the three modes, wherein the
front sleeve portion is moveable along the second longitudinal axis
to selectively couple the spindle drive mechanism to the
intermediate shaft when in the drilling mode and the hammering and
drilling mode to transmit rotary movement of the intermediate shaft
to rotary movement of the spindle and to selectively decouple the
spindle drive mechanism from the intermediate shaft when in the
hammering mode so that rotation of the intermediate shaft does not
cause rotation of the spindle, and wherein the rear sleeve portion
is moveable along the second longitudinal axis to selectively
couple the piston drive mechanism to the intermediate shaft when in
the hammering and drilling mode and the hammering mode to transmit
rotary movement of the intermediate shaft to reciprocating movement
of the piston and to selectively decouple the piston drive
mechanism from the intermediate shaft when in the drilling mode so
that rotation of the intermediate shaft does not cause
reciprocating movement of the piston; an actuator switch moveable
among three positions corresponding to the drilling mode, the
hammering and drilling mode, and the hammering mode; and a linkage
that links the actuator switch to the mode change mechanism to
effectuate the movement of the front and rear sleeve portions upon
movement of the actuator switch. .Iaddend.
.Iadd.23. The rotary hammer according to claim 22, wherein the
front sleeve portion comprises a projection that can be selectively
engaged with a recess on the spindle driving member when the mode
change mechanism is in the drilling mode and the drilling and
hammering mode. .Iaddend.
.Iadd.24. The rotary hammer according to claim 22, wherein the rear
sleeve portion comprises a projection that can be selectively
engaged with a recess on the hammer driving member when the mode
change mechanism is in the hammering mode and the drilling and
hammering mode. .Iaddend.
.Iadd.25. The rotary hammer according to claim 24, wherein the
front sleeve portion comprises a projection that can be selectively
engaged with a recess on the spindle driving member when the mode
change mechanism is in the drilling mode and the drilling and
hammering mode. .Iaddend.
.Iadd.26. The rotary hammer according to claim 22, wherein the
linkage comprises a bar that extends substantially parallel to the
second longitudinal axis and at least one arm that extends
laterally from the bar, the at least one arm being coupled to the
mode change mechanism such that shifting of the bar along the
second longitudinal axis moves the mode change mechanism among the
drilling mode, the drilling and hammering mode, and the hammering
mode. .Iaddend.
.Iadd.27. The rotary hammer according to claim 22, wherein the
actuator switch comprises a rotatable knob mounted on the housing
and an eccentric pin coupled to the rotatable knob, wherein when
the rotatable knob is rotated the eccentric pin is rotated and
slideably engages with the linkage in order to shift the mode
change mechanism among the drilling mode, the drilling and
hammering mode, and the hammering mode. .Iaddend.
.Iadd.28. The rotary hammer according to claim 22, further
comprising a spring that biases the mode change mechanism toward
one of the drilling mode, the drilling and hammering mode, and the
hammer mode. .Iaddend.
.Iadd.29. The rotary hammer according to claim 28, wherein the
spring biases the front sleeve portion of the mode change mechanism
to couple the intermediate shaft to the spindle drive mechanism.
.Iaddend.
.Iadd.30. The rotary hammer according to claim 28, wherein the
spring biases the rear sleeve portion of the mode change mechanism
to couple the intermediate shaft to the piston drive mechanism.
.Iaddend.
.Iadd.31. The rotary hammer according to claim 22, further
comprising a spindle lock member to lock the spindle against
rotation when the rotary hammer is in the hammering mode.
.Iaddend.
.Iadd.32. The rotary hammer according to claim 31, wherein the
spindle lock member comprises a set of teeth that are fixed against
rotation and that are moveable substantially parallel to the second
longitudinal axis with the linkage to bring the set of teeth into
engagement with the spindle drive mechanism. .Iaddend.
.Iadd.33. The rotary hammer according to claim 22, further
comprising a ram that is reciprocally driven by the piston through
an air cushion, and an anvil that is repeatedly impacted by the ram
and that, in turn, impacts the tool held in the tool holder.
.Iaddend.
.Iadd.34. The rotary hammer according to claim 22, wherein the
intermediate shaft is substantially parallel to the spindle.
.Iaddend.
.Iadd.35. The rotary hammer according to claim 22, wherein the
spindle drive mechanism comprises a first splined ring gear that is
permanently fixed to the spindle and a second splined ring gear
that engages the first splined ring gear, wherein the front sleeve
portion of the mode change mechanism causes the second splined ring
gear to rotate with the intermediate shaft. .Iaddend.
.Iadd.36. The rotary hammer according to claim 22, wherein the
piston drive mechanism comprises a wobble drive mechanism that
converts rotary motion of the intermediate shaft to reciprocal
motion of the piston. .Iaddend.
.Iadd.37. The rotary hammer according to claim 22, wherein the
actuator includes a releasable detent arrangement that releasably
latches the actuator in at least one of the three positions.
.Iaddend.
.Iadd.38. The rotary hammer according to claim 22, wherein front
sleeve portion and the rear sleeve portion are disposed on a single
mode change sleeve. .Iaddend.
Description
BACKGROUND OF THE INVENTION
This invention relates to a rotary hammer, and particularly relates
to a rotary hammer with a mode change mechanism for switching the
rotary hammer for operation in any one of a hammer only mode, a
rotary drive only mode and a rotary hammering mode.
In a hammer only mode of a conventional rotary hammer, a bit is
inserted into a tool holder of the hammer and is repeatedly struck
by a hammering mechanism and is not rotatably driven. In a rotary
drive only mode, the bit is rotatably driven and is not subject to
impacts from the hammering mechanism. In a rotary hammering mode,
the bit is repeatedly struck by the hammering mechanism and is
simultaneously rotatably driven.
Conventional rotary hammers of this type typically include a
spindle mounted for rotation within a housing of the hammer which
can be driven by a rotary drive arrangement, selectively engageable
and disengageable with a pinion driven by a motor of the hammer.
The spindle rotatably drives a tool holder of the hammer which in
turn rotatably drives a tool or bit releasably secured within the
hammer. A piston is generally slideably located within the spindle
and is reciprocally driven by a hammer drive mechanism which
translates the rotary drive of a hammer motor to a reciprocating
drive of the piston. A ram, also slideably located within the
spindle, forward of the piston, follows the reciprocation of the
piston due to successive reversing pressures in an air cushion
within the spindle between the piston and the ram. The ram
repeatedly impacts an anvil slideably located within the spindle
forward of the ram which transfers the forward impacts from the ram
to the tool or bit, for limited reciprocation within the tool
holder at the front of the hammer. The mode change mechanisms for
such hammers can selectively engage and disengage the rotary drive
to the spindle and the reciprocating drive to the piston.
In a known type of mode change mechanism, a single mode change
actuator is used to switch the hammer between different modes.
However, mechanisms of this type tend to be relatively complex, use
parts which are intricate and/or difficult to manufacture
inexpensively in bulk, with sturdy qualities that can withstand
sustained use of the hammer, and/or are relatively difficult to
assemble.
A known mode change arrangement is disclosed in U.S. Pat. No.
5,159,986, and includes a mode change knob having a first cam
element for activating and de-activating hammering, and a second
cam for activating and deactivating rotary drive. The disclosed
arrangement also includes the option of operating at either of two
drive speeds. In a first position of the first cam element,
rearward movement of the spindle is blocked, which prevents the
drive from being transmitted to the hammer drive arrangement. In a
second position of the first cam, rearward movement of the spindle
occurs when the tool or bit is pressed against a work surface. This
rearward movement of the spindle results in the engagement of two
coupling parts which allows the drive to be transmitted from an
intermediate shaft to the hammer drive arrangement.
The second cam arrangement, as described in U.S. Pat. No.
5,159,986, is used to guide an adjustment element along a rod
mounted in the housing of the hammer, which adjustment element
engages spindle drive gears to shift the gears between three
positions. In a first of the three positions, a drive gear engages
a spindle lock to prevent rotation of the spindle, and relates to
of a surface of the first cam whereby drive is transmitted to the
hammer drive arrangement. In a second position, a first drive gear
engages the intermediate shaft to drive the spindle at a first
speed of rotation, and, in a third position, a second drive gear
engages the intermediate shaft to drive the spindle at a second
speed. The three positions of the drive gears, as they relate to
the orientation of the second cam element, are co-ordinated with
the blocking and non-blocking positions, in relation to the
orientation of the first cam element, in order to co-ordinate the
activation of the spindle at the required speed with the activation
of hammering.
The mode change arrangement as disclosed in U.S. Pat. No. 5,159,986
requires many non-standard type parts such as the first and second
cam surfaces, an adjustment element, a bearing and a cage, which
have to interact to change between the modes of operation. Such
parts are relatively expensive to manufacture in such a way that
the parts can survive sustained use of the hammer and still provide
smooth changes between the different modes of operation of the
hammer. Also, the assembling of the parts to provide such a mode
change arrangement is relatively difficult, which further adds to
the cost of manufacturing such hammers. Further, a biasing means
between the knob and the adjustment element is required to bias the
gears or teeth into position for meshing until one of the gears has
rotated sufficiently to allow actual meshing to occur. This results
in additional cost and complexity.
SUMMARY OF THE INVENTION
Therefore, it is an object of this invention to provide a rotary
hammer having a simple and reliable mode change mechanism for
selectively operating in a hammer only mode, a rotary hammer mode,
or a rotary drive only mode.
Another object of this invention is to provide a rotary hammer
having a mode change mechanism which utilizes primarily standard
engineering parts such as splined shafts, gear wheels, splined
sleeves and springs.
A further object of this invention is to provide a rotary hammer
having a mode change mechanism which utilizes primarily standard
engineering parts which are sturdy and inexpensive to manufacture,
and relatively easy to assemble.
With these and other objects in mind, this invention contemplates a
rotary hammer, which includes an intermediate shaft rotatably
drivable by a motor, and a spindle which can be driven about an
axis thereof by the intermediate shaft through a spindle drive
arrangement. The rotary hammer further includes a tool holder
arranged for rotation with the spindle for releasibly holding a bit
or a tool for reciprocation, a pneumatic hammering arrangement
located within the spindle which can repeatedly impact the bit or
tool held within the tool holder. The pneumatic hammering
arrangement includes a piston which can be reciprocally driven by a
hammer drive arrangement for translating rotary drive from the
intermediate shaft to a reciprocating drive for the piston. The
rotary hammer further includes a mode changing mechanism for
changing the operation of the hammer amongst a hammer only mode, a
rotary hammer mode, and a rotary drive only mode. The mode change
mechanism includes a spindle driving member rotatably mounted on
the intermediate shaft for driving the spindle drive arrangement, a
hammer driving sleeve rotatably mounted on the intermediate shaft
for driving the hammer drive arrangement, and a mode change sleeve,
which surrounds the intermediate shaft and which is permanently
driven by and shiftable along the intermediate shaft. The switching
of the actuator by a user shifts the mode change sleeve along the
intermediate shaft to any one of three positions, such that, in a
first rotary drive only position, the mode change sleeve transmits
rotary drive to the spindle driving member and to transmit rotary
drive to the spindle drive arrangement. In a second hammer only
position, the mode change sleeve transmits rotary drive to the
hammer driving sleeve to transmit rotary drive to the hammer drive
arrangement. In a third rotary hammer position, the mode change
sleeve transmits rotary drive to the spindle driving member and to
the hammer driving sleeve to transmit rotary drive to the spindle
drive arrangement and to the hammer drive arrangement.
This invention further contemplates the mounting of the hammer
drive sleeve and the spindle drive member rotatably on the
intermediate shaft, and the mounting of the mode change sleeve
shiftably and non-rotatably along the intermediate shaft. This
facilitates use of the mode change sleeve to transfer rotary drive
from the intermediate shaft to the hammer drive sleeve and/or the
spindle drive member by simply shifting the mode change sleeve
along the intermediate shaft to selectively engage the hammer drive
sleeve and/or the spindle drive member. The parts required for this
mode change mechanism are standard engineering parts, such as a
shaft and sleeves rotatable or non-rotatable on the shaft and
optionally shiftable along the shaft. The sleeves have parts such
as gear wheels or teeth, which are selectively engageable with each
other. Such parts can be manufactured inexpensively and of sturdy
structure, and can be easily assembled to provide a simple and
reliable mode change mechanism.
In further contemplation of this invention, preferably, an
intermediate shaft driving member, preferably a gear which is
non-rotatable on the intermediate shaft, is in permanent engagement
with a mode change sleeve driven member, preferably a set of teeth
on the mode change sleeve, so that rotation of the intermediate
shaft rotatingly drives the mode change sleeve.
Still, in further contemplation of this invention, in a preferred
arrangement, the hammer drive sleeve is located towards the rear of
the mode change sleeve and has a driven member, preferably a set of
teeth, which is engageable with a driving member, also preferably a
set of teeth, on the mode change sleeve to transmit rotary drive
from the intermediate shaft to the hammer drive sleeve. Preferably,
the mode change sleeve driven member, which engages the
intermediate shaft driving member, is axially extended and also
forms the mode change sleeve driving member, which is engageable
with the hammer drive sleeve driven member, to transmit rotary
drive from the intermediate shaft to the hammer drive arrangement.
Using a single extended driven and driving member, such as an
extended set of teeth, again simplifies the structure of the mode
change sleeve.
This invention also contemplates, in a preferred arrangement, the
spindle drive member being located towards the front of the mode
change sleeve and has a driven member, preferably a set of teeth,
on the mode change sleeve to transmit rotary drive from the
intermediate shaft to the spindle drive member. Again, it is
preferred that the mode change sleeve driven member which engages
the intermediate shaft driving member is axially extended to also
form the mode change sleeve driving member which is engageable with
the spindle drive member to transfer rotary drive from the
intermediate shaft to the spindle drive member. Using a single
extended driven and driving member, such as an extended set of
teeth, again simplifies the structure of the mode change
sleeve.
The spindle drive member may be a spindle drive sleeve which is
rotatably mounted on the outside of the intermediate shaft.
Alternatively, the spindle drive member may be a spindle drive
pinion which is rotatably mounted within the front end of the
intermediate shaft.
When the above preferred arrangements are both used on the hammer,
the mode change mechanism is arranged such that, in a first rotary
drive only position, the mode change sleeve is shifted to a forward
position on the intermediate shaft to transmit rotary drive to the
spindle driving member by way of the mode change sleeve driving
member and the spindle drive member driven member. In a second
hammer only position, the mode change sleeve is shifted to a
rearward position on the intermediate shaft to transmit rotary
drive to the hammer driving sleeve by way of the mode change sleeve
driving member and the hammer drive sleeve driven member. In a
third rotary hammer position, the mode change sleeve is shifted to
an intermediate position on the intermediate shaft between the
forward and rearward positions and transmits rotary drive to the
spindle driving member and transmits rotary drive to the hammer
driving sleeve.
In a preferred embodiment, the switching of the single actuator
shifts the mode change sleeve by way of a mode change member. The
mode change member may be mounted on a housing part of the hammer
so as to be slideable in a direction substantially parallel to the
intermediate shaft. The mode change member is preferably provided
with a mode change arm, preferably a ring, which extends laterally
of the mode change member. The mode change arm at least partly
surrounds at least a part of the mode change sleeve and is
connected to the mode change sleeve such that shifting of the mode
change member shifts the mode change sleeve by way of the mode
change arm amongst the three positions.
In order to insure transmission of rotary drive between the parts,
which may not initially be in meshing alignment when the hammer is
first switched to one of the three modes of operation, a biasing
arrangement is located between the actuator and the mode change
sleeve in order to bias the sleeve towards a position on the
intermediate shaft which corresponds to the position to which the
actuator is switched. When the hammer includes a mode change member
having a mode change arm as described above, it is preferred that
the biasing arrangement includes a first spring means located
between a forward end of the mode change sleeve and a forward
facing part of the mode change arm and a second spring means
located between a rearward end of the mode change sleeve and a
rearward facing part of the mode change arm.
Preferably, a spindle lock is provided on the hammer to lock the
spindle against rotation when the hammer is in the hammer only
mode. When the hammer includes a mode change member, as described
above, it is preferred that the spindle lock include a first
locking means located on the mode change member, which first
locking means is engageable with a second locking means provided on
the spindle when the mode change member is shifted to a hammer only
mode position to lock the spindle against rotation.
The actuator may be a rotatable knob mounted on a housing part of
the hammer such that the rotation of the knob rotates an eccentric
pin which pin is slideably engaged, preferably with a slot in the
mode change member, in order to shift the mode change member and
thereby shift the mode change sleeve amongst the three mode
positions.
The mode change mechanism described above is suited to the type of
hammer having a pneumatic hammering arrangement which includes a
reciprocally driven piston, which reciprocally drives a ram by way
of a closed air cushion. The ram repeatedly impacts an anvil which
is driven, in a forward direction, to impact a bit or tool held in
the tool holder. This arrangement is particularly suited to the
type of hammer in which the intermediate shaft is substantially
parallel to the spindle.
It is preferred that the spindle drive member include a driving
member, preferably a gear, which is in permanent engagement with
the spindle drive engagement, which preferably includes a gear.
It is also preferred that the hammer drive arrangement is a wobble
plate drive arrangement.
Preferably, a releasable detent arrangement is provided for
releasably latching the actuator in the required mode switch
position. This is important if the hammer includes means for
biasing the mode change mechanism into meshing engagement when the
meshing parts are initially not aligned.
Other objects, features and advantages of the present invention
will become more fully apparent from the following detailed
description of the preferred embodiment, the appended claims and
the accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
In the accompanying drawings:
FIG. 1 is an exploded perspective view showing a layout of the
components of a rotary hammer mode change mechanism in accordance
with certain principles of the invention;
FIG. 2a is a sectional view showing a first embodiment of a rotary
hammer, including the mode change mechanism of FIG. 1, in a rotary
drive only mode, or drilling mode, in accordance with certain
principles of the invention;
FIG. 2b is a sectional view showing the rotary hammer of FIG. 2a,
including the mode change mechanism of FIG. 1, in a rotary hammer
mode in accordance with certain principles of the invention;
FIG. 2c is a sectional view showing the rotary hammer of FIG. 2a,
including the mode change mechanism of FIG. 1, in a hammer only
mode in accordance with certain principles of the invention;
FIG. 3 is a sectional view showing a second embodiment of a rotary
hammer, including the mode change mechanism of FIG. 1, in a hammer
only mode in accordance with certain principles of the
invention;
FIG. 4a is a sectional view showing the rotary hammer of FIG. 3,
including the mode change mechanism of FIG. 1, in a rotary hammer
mode in accordance with certain principles of the invention;
and
FIG. 4b is a sectional view showing the rotary hammer of FIG. 3,
including the mode change mechanism of FIG. 1, in a rotary drive
only mode, or a drilling only mode, in accordance with certain
principles of the invention.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS OF THE
INVENTION
Referring to FIGS. 1, 2a, 2b and 2c, a first embodiment of a rotary
hammer includes a forward housing part 2 and a central housing part
4, which are held together by threaded fasteners (not shown) to
form a housing for a hammer spindle, a spindle drive arrangement, a
hammer drive arrangement and a mode change mechanism. A resilient
housing seal 6 fits between the housing parts 2 and 4 in a
complementary recess provided in co-operating end surfaces of the
housing parts to form a seal between the housing parts. The housing
parts 2 and 4 are each formed with semi-circular recesses 2a and
4a, respectively, which co-operate to form a circular recess, lined
with a ring section 6a of the housing seal 6, within which a mode
change knob 8 is mounted for rotation about a mode change axis 12.
The mode change knob 8 has an axle with an enlarged portion 10
which is captured within the hammer housing when the housing parts
2 and 4 are assembled together. In this manner, the mode change
knob 8 is secured to the hammer housing. An eccentric pin 14 is
formed with and extends from an end of the mode change axle for
slideably moving a mode change member 68, as described below.
The rotary hammer includes a spindle 18 which is mounted for
rotation within the hammer housing in a conventional manner. Also,
a hollow piston 20 is located slideably within the rear of the
spindle 18 in a conventional manner. The hollow piston 20 is
reciprocated within the spindle 18 by a hammer drive arrangement as
described in more detail below. A ram 21 follows the reciprocation
of the piston 20 in the usual manner due to successive reversing
pressures in an air cushion within the spindle 18 between the
piston and the ram. The reciprocation of the ram 21 causes the ram
to repeatedly impact an anvil 22 which repeatedly impacts a tool or
bit (not shown). The tool or bit is releasably secured to the
rotary hammer by a tool holder of conventional design, such as and
SDS-Plus type tool holder 16, which enables the tool or bit to
reciprocate within the tool holder to transfer the forward impact
of the anvil 22 to a surface to be worked, such as a concrete
block. The tool holder 16 also transmits rotary drive from the
spindle 18 to the tool or bit secured within the tool holder.
The rotary hammer is driven by a motor (not shown), which has a
pinion (not shown) for rotatably driving an intermediate shaft 24
by way of a drive gear 32. The intermediate shaft 24 is mounted for
rotation within the hammer housing, parallel to the hammer spindle
18 by means of a rearward bearing 26 and a forward bearing 28. A
spring washer 30 urges the intermediate shaft 24 rearwardly and is
used to damp any reciprocatory motion which is transmitted to the
intermediate shaft by way of a wobble plate hammer drive
arrangement described below. The intermediate shaft 24 has a
driving gear 50, either integrally formed therewith or press fit
onto shaft so that the driving gear rotates with the shaft. Thus,
whenever power is supplied to the motor, the driving gear 50
rotates along with the intermediate shaft 24.
The hammer drive arrangement includes a hammer drive sleeve 34
which is rotatably mounted on the intermediate 24 and which has a
wobble plate track 36 formed around the sleeve at an angle to the
axis of the intermediate shaft. A wobble plate ring 38, having an
extending pin 40, is mounted for rotation around the wobble plate
track 36 by way of ball bearings 39 in a conventional manner. The
end of the wobble pin 40, remote from the wobble plate ring 38, is
mounted through an aperture in a trunnion 42 which is pivotally
mounted to the rear end of the hollow piston 20 by way of two arms
44 having aligned apertures formed therethrough. Thus, when the
hammer drive sleeve 34 is rotatably drive about the intermediate
shaft 24, a wobble plate drive (which is formed by the wobble plate
track 36, the wobble plate ring 38, the ball bearings 39, the
wobble pin 40, the trunnion 42 and the arms 44) reciprocally drives
the hollow piston 20 in a conventional manner. The hammer drive
sleeve 34 has a set of driven splines 48 formed on a forward end of
the sleeve. The driven splines 48 are selectively engageable with
the driving gear 50 by way of the mode change mechanism described
below. When the intermediate shaft 24 is rotatably driven by the
motor pinion, and the mode change mechanism engages the driving
splines 48 of the hammer drive sleeve 34, (1) the driving gear 50
rotatably drives the hammer drive sleeve, (2) the piston 20 is
reciprocally driven by the wobble plate drive, and (3) the tool or
bit mounted in the tool holder 16 is repeatedly impacted by the
anvil 22 by way of the action of the ram 21.
The spindle drive member includes a spindle drive sleeve 56 which
is mounted for rotation about the intermediate shaft 24. The
spindle sleeve 56 includes a set of driving teeth 60 at the forward
end thereof which are permanently in engagement with the teeth of a
spindle drive gear 62. The spindle drive gear 62 is mounted
non-rotatably on the spindle 18 by way of a driving gear 64 which
has a set of teeth formed on the internal circumferential surface
thereof which are permanently engaged with a set of drive teeth 66
formed on the outer cylindrical surface of the spindle 18. Thus,
when the spindle drive sleeve 56 is rotatably driven, the spindle
18 is rotatably driven, and this rotary drive is transferred to the
tool or bit by way of the tool holder 16. The drive sleeve 56 has a
driven gear 58 located at a rearward end of the drive sleeve which
can be selectively driven by the intermediate shaft driving gear 50
by way of the mode change mechanism.
The mode change mechanism, which can be used to selectively actuate
the hammer drive arrangement and/or the spindle drive arrangement,
includes the mode change member 68 which is slideably mounted
within the housing on guide members (not shown) mounted within or
formed integrally with the housing. The mode change member 68 is
formed with a set of spindle lock teeth 70 which can be selectively
engaged with the spindle drive gear 62 to lock the spindle, against
rotation, by way of the drive gear. The mode change membr 68 has a
mode change ring 72 secured to a central region thereof so that the
ring extends laterally of the member. The mode change ring 72 is
slideably mounted over a mode change sleeve 52. A pair of coil
springs, forward spring 76 and rearward spring 78, are mounted
surrounding the mode change sleeve 52 in order to position the mode
change ring 72 with respect to the mode change sleeve. The forward
spring 76 acts between an annular flange 84, located towards the
forward end of the mode change sleeve 52, and the forward annular
face of the mode change ring 72. The rearward spring 78 acts
between the rearward annular face of the mode change ring 72 and a
stop ring 80, which is mounted towards the rearward end of the mode
change sleeve 52 by a snap ring 82.
The mode change member 68 is formed with a slot 74 which extends in
a direction substantially perpendicular to the direction of sliding
of the mode change member. The eccentric pin 14 of the mode change
knob 8 is slideably received within the slot 74 in the mode change
member 68. In this manner, as the mode change knob 8 is rotated by
the user of the hammer about the axis of the knob, the eccentric
pin slides along the slot 74. This causes the mode change member 68
to slide forwards or backwards within the housing in order to move
the mode changing ring 72 forwards or backwards with respect to the
intermediate shaft 24 and to move the spindle lock teeth 70
forwards or backwards with respect to the spindle drive gear
62.
A detent arrangement includes a spring 90 and a ball bearing 92 and
is situated in a bore 94 provided in the housing part 4 so that the
ball bearing is urged by the spring into one of a number of pockets
(not shown) which are provided in the underside of the knob 8. Each
pocket is positioned so that it corresponds to a mode position of
the knob 8, with the ball bearing 92 resting in a first-elected one
of the pockets which is associated with the most recently selected
mode of operation. When the knob 8 is moved toward one of the other
mode positions in order to change the operating mode of the rotary
hammer to a newly selected mode position, a user must overcome the
biasing force of the spring 90 to push the ball bearing 92 out of
the first-elected one of the pockets in the underside of the knob.
Once the knob 8 is moved into the newly selected mode position, the
ball bearing 92 is urged by the spring 90 to engage a
second-selected one of the pockets which corresponds to the newly
selected mode position. Once the ball seats in the second-selected
one of the pockets, the knob 8 is latched against movement out of
the newly selected mode position.
As shown in FIG. 2a, the rotary hammer is in the rotary drive only
mode in which the spindle 18 is driven rotationally and the hammer
drive arrangement is disengaged. The mode change knob 8 is in the
farthest position to which it can be rotated in a clockwise
direction and so the eccentric pin 14 lies forwardly of the axis 12
of the knob and maintains the mode change member 68 in the
forwardmost position. In this position, the spindle lock teeth 70
are located forward of the spindle drive gear 62 which is free to
rotate in order to rotationally drive the spindle 18. The mode
changing ring 72 is in its forwardmost position and urges the mode
change sleeve 52 forwardly by way of the spring 76. In this manner,
the internal teeth 54 of the sleeve 52 are disengaged from the
hammer drive splines 48 on the hammer drive sleeve 34 and so that
the internal teeth 54 of the mode change sleeve 52 are engaged with
the driving gear 50 on the intermediate shaft 24 and the driven
gear 58 on the spindle drive sleeve 56.
As the internal teeth 54 are disengaged from the hammer drive
splines 48, rotation of the intermediate shaft 24 is not
transmitted to the hammer drive sleeve 34 which remains stationary
as the intermediate shaft is rotated by the motor. Thus, no
hammering action occurs. However, the engagement of the internal
teeth 54 of the mode change sleeve 52 with the driving gear 50 of
the intermediate shaft 24 and the driven gear 58 of the spindle
drive sleeve 56 transmits rotary drive from the intermediate shaft
to the spindle drive sleeve. This rotary drive is then transmitted
to the spindle 18 by way of the driving teeth 60 on the spindle
drive sleeve 56, the spindle drive gear 62 and the spindle drive
ring 64. Accordingly, the rotary hammer operates in the rotary
drive only or drilling mode.
The rotary hammer is moved into rotary drive only mode by rotating
the mode change knob 8 clockwise, and the knob is latched in its
rotary drive only position by the detent arrangement 90 and 92.
When the rotary hammer is moved into the rotary drive only mode
from the hammer only mode as the knob 8 is rotated clockwise, it is
possible that the internal teeth 54 of the mode change sleeve 52
are not in alignment with the teeth 60 of the drive gear 58 of the
spindle drive sleeve 56. If this is so, then as the mode change
ring 72 is shifted forwardly and the forward movement of the mode
change sleeve 52 is blocked by the mis-aligned teeth, the spring 76
is compressed and acts to urge the mode change sleeve toward its
forward position. Thus, with the knob 8 latched in the rotary drive
only position, as soon as the intermediate shaft 24 has rotated by
a small angle required to align the internal teeth 54 with the
teeth of the driven gear 58, the spring 76 urges the mode change
sleeve 52 forwardly into the position shown in FIG. 2a so that the
internal teeth 54 of the mode change sleeve 52 mesh with the drive
gear 58 of the spindle drive gear 56. Thereafter, rotation of the
intermediate shaft 24 is transmitted to the spindle 18.
As shown in FIG. 2b, the rotary hammer is in the rotary hammer mode
in which the spindle 18 is driven rotationally and the hammer drive
is engaged. The mode change knob 8 is in an intermediate position
and the eccentric pin 14 is located above the axis 12 of the mode
change knob and maintains the mode change member 68 in an
intermediate position. In this position, the spindle lock teeth 70
remain located forward of the spindle drive gear 62, which is free
to rotate in order to rotationally drive the spindle 18. The mode
change ring 72 is in an intermediate position and urges the mode
change sleeve 52 into an intermediary position by way of the spring
76 or the spring 78, depending on the previous mode of operation of
the rotary hammer. In this intermediate position, the internal
teeth 54 of the sleeve 52 are engaged with the hammer driven
splines 48 on the hammer drive sleeve 34 and with the driving gear
58 on the spindle drive sleeve 56.
As the internal teeth 54 are engaged with the hammer driven splines
48, rotation of the intermediate shaft 24 is transmitted to the
hammer drive sleeve 34 which rotates with the intermediate shaft.
Thus, rotary drive from the motor is translated into a
reciprocating drive of the hollow piston 20 by way of the driving
gear 50 of the intermediate shaft, the mode change sleeve 52, the
hammer driven splines 48 on the hammer drive sleeve 34 and the
wobble plate mechanism, whereby hammering action occurs. The
engagement of the internal teeth 54 of the mode change sleeve 52
with the driving gear 50 of the intermediate shaft 24 and the
driven gear 58 of the spline drive sleeve 56 transmits rotary drive
from the intermediate shaft to the spindle drive sleeve 52. This
rotary drive is then transmitted to the spindle 18 by way of the
driving teeth 60 on the spindle drive sleeve 56, the spindle drive
gear 62 and the spindle drive ring 64. Accordingly, the rotary
hammer operates in the rotary hammer mode. Note that the rotary
hammer can be moved into the rotary hammer mode by rotating the
mode change knob 8 either counter-clockwise from the rotary drive
only position or clockwise from the hammer only mode position.
When the rotary hammer is moved into the rotary hammer mode from
the rotary drive only mode as the knob 8 is rotated in a
counter-clockwise direction, it is possible that the internal teeth
54 of the mode change sleeve 52 are not in alignment with the
driven splines 48 of the hammer drive sleeve 34. In this instance,
as the mode change ring 72 is shifted rearwardly and the rearward
movement of the mode change sleeve 52 is blocked by the mis-aligned
teeth, the spring 78 is compressed and acts to urge the mode change
sleeve 52 towards the its intermediate position. Thus, with the
knob 8 latched in the rotary hammer position, as soon as the
intermediate shaft 24 has rotated by the small angle required to
align the splines 48 of the hammer driving sleeve 34 with the
internal teeth 54 of the mode change sleeve 52, the spring 78 urges
the mode change sleeve rearwardly into the position shown in FIG.
2b so that the internal teeth 54 mesh with the splines 48.
Thereafter, rotation of the intermediate shaft 24 is transmitted to
the hammer drive arrangement as well as to the spindle drive
arrangement.
When the rotary hammer is moved to the rotary hammer mode from the
hammer only mode as the knob 8 is rotated clockwise, it is possible
that the internal teeth 54 of the mode change sleeve 52 are not in
alignment with the teeth of the driven gear 58 of the spindle drive
sleeve 56. If this is so, as the mode change ring 72 is shifted
forwardly and the forward movement of the mode change sleeve 52 is
blocked by the mis-aligned teeth, the spring 76 is compressed and
acts to urge the mode change sleeve 52 towards its intermediate
position.
Thus, with the knob 8 latched in the rotary hammer position, as
soon as the intermediate shaft 24 has rotated by the small angle
required to align the teeth of the spindle drive sleeve 58 with the
internal driving teeth 54 of the mode change sleeve 52, the spring
76 urges mode change sleeve forwardly into the position shown in
FIG. 2b so that the internal teeth 54 of the mode change sleeve
meshes with the teeth of the spindle drive gear 58. Thereafter,
rotation of the intermediate shaft 24 is transmitted to the spindle
drive arrangement as well as to the hammer drive arrangement.
As shown in FIG. 2c, the rotary hammer is in the hammer only mode
in which the spindle 18 is locked against rotation and the hammer
drive arrangement is engaged. The mode change knob 8 is latched in
the farthest position to which it can be rotated in a
counter-clockwise direction where the eccentric pin 14 is
rearwardly of the axis 12 of the mode change knob and maintains the
mode change member 68 in its rearward most position. In this
position, the spindle lock teeth 70 are in engagement with the
spindle drive gear 62, where the spindle drive gear and the spindle
18 are locked against rotation.
In the hammer only mode, the mode change ring 72 is in its rearmost
position and urges the mode change sleeve 52 rearwardly by the way
of the spring 78 so that the internal teeth 54 of the drive sleeve
52 are engaged with the hammer drive splines 48 on the hammer drive
sleeve 34, whereby the internal teeth 54 are disengaged from the
driven gear 58 on the spindle drive sleeve 56. As the internal
teeth 54 engage with the hammer drive splines 48, rotation of the
intermediate shaft 24 is transmitted to the hammer drive sleeve 34,
which rotates the intermediate shaft. This rotational drive to the
hammer drive sleeve 34 is translated into reciprocating drive for
the piston 20 by way of the hammer drive arrangement. Thus,
hammering action occurs. The disengagement of the internal teeth 54
of the mode change sleeve 52 from the driven gear 58 of the spindle
drive sleeve 56 facilitates that no rotary drive is transmitted
from the intermediate shaft 24 to the spindle drive sleeve which,
therefore, remains stationary as the intermediate shaft rotates.
Accordingly, the rotary hammer operates in the hammer only
mode.
The rotary hammer is moved into the hammer only mode by rotating
the mode change knob 8 counter-clockwise. When the rotary hammer is
moved into the hammer only mode from the rotary drive only mode as
the knob 8 is rotated counter-clockwise, it is possible that the
internal teeth 54 of the mode change sleeve 52 are not in alignment
with the driven splines 48 on the hammer drive sleeve 34. If this
is the case, then as the mode change ring 72 is shifted rearwardly
and the rearward movement of the mode change sleeve 52 is blocked
by the mis-aligned teeth, the spring 78 is compressed and acts to
urge the mode change sleeve towards its rearmost position. Thus,
with the knob 8 latched in the hammer only position, as soon as the
intermediate shaft 24 has rotated by the small angle required to
align the internal teeth 54 with the driven splines 48 of the
hammer drive sleeve 34, the spring 78 urges the mode change sleeve
52 rearwardly into the position shown in FIG. 2c, so that the
internal teeth 54 mesh with the driven splines. Thereafter,
rotation of the intermediate shaft 24 is transmitted to the hammer
drive sleeve 34.
A second embodiment of a rotary hammer having a mode change
mechanism according to the present invention is shown in FIGS. 3,
4a and 4b. The second embodiment is similar to the first embodiment
of the rotary hammer, with like parts identified by like numerals,
the difference being that the spindle drive member is a spindle
drive pinion 56'. As shown in FIGS. 3, 4a and 4b, the front end of
a motor drives the intermediate shaft 24 of the rotary hammer by
way of a motor pinion 23 and the drive gear 32 of the intermediate
shaft. In this way, the intermediate shaft 24 is always driven in
rotation when the motor is switched on. The spindle drive pinion
56' has a rearward axial projection 70 which is rotatably mounted
within a co-operating recess 72 within the front part of the
intermediate shaft 24 by way of a needle bearing 74. Thus, the
spindle drive pinion 56' can rotate relative to the intermediate
shaft 24. The forward end of the spindle drive pinion 56' is
rotatably mounted in a bearing 28 mounted in the rotary hammer
housing. In the same way described above, rotary drive is
transmitted from the intermediate shaft 24 to the spindle drive
pinion 56' by the mode change sleeve 52 to rotatably drive the
spindle 18 by way of the spindle drive gear 62.
The hammer drive sleeve 34 is rotatably mounted on the intermediate
shaft 24 by way of needle bearings 76 and 78. Again, the hammer
drive sleeve 34 can be selectively rotationally driven by the
intermediate shaft 24 by way of the mode change sleeve 52 to
initiate the hammering operation. The mode change sleeve 52 is
axially switchable by an actuator linkage, similar to the type
described above, between three positions to hammer only mode (FIG.
3), rotary hammer mode (FIG. 4a) and rotary drive only or drill
only mode (FIG. 4b), in the manner described above.
.Iadd.The hammer drive sleeve 34 and intermediate shaft are
supported by an intermediate support bearing arrangement 129. The
hammer drive sleeve 34 has formed on its external surface,
forwardly of the wobble bearing arrangement 36, 38, 39, an annular
channel 140 within which runs a set of bearing balls 142. The
bearing balls 142 run between an inner race formed within the
annular channel 140 of the hammer drive sleeve 34 and an outer race
144 formed in a bearing ring 146. The bearing ring 146 is used to
support the intermediate shaft 24 and hammer drive sleeve 34 within
the housing 2, 4. Thus, the intermediate shaft 24 is supported in
the housing parts 2 and 4 by the rearward bearing 26, the forward
bearing 28, and the intermediate support bearing arrangement 129
via the hammer drive sleeve 34. .Iaddend.
While the embodiments described above refer to rotary hammers
within which the motor is in line with the hammer spindle (i.e.,
parallel thereto), the mode change mechanism is also suitable for
the so called L-shaped hammers in which the axis of the motor is
perpendicular to the spindle. In such L-shaped rotary hammers, the
motor pinion will extend into the hammer housing from below and
will mesh with an intermediate shaft drive gear (replacing the gear
32) which is a bevel gear.
In general, the above-identified embodiments are not to be
construed as limiting the breadth of the present invention.
Modifications, and other alternative constructions, will be
apparent which are within the spirit and scope of the invention as
defined in the appended claims.
* * * * *