U.S. patent number 3,559,585 [Application Number 04/811,469] was granted by the patent office on 1971-02-02 for power and free conveyor.
This patent grant is currently assigned to Jervis B. Webb Company. Invention is credited to George D. Lempio.
United States Patent |
3,559,585 |
Lempio |
February 2, 1971 |
**Please see images for:
( Certificate of Correction ) ** |
POWER AND FREE CONVEYOR
Abstract
A conveyor of the power and free type having a power track for a
propelling member spaced above a carrier supporting track. Each
carrier is provided at the front end with a rigid main driving dog
and at the rear end with a rid combination releasing cam and
auxiliary driving dog. Forwarding motion is imparted to a carried
by a pusher unit on the propelling member, the pusher unit
including an auxiliary driving face and a movable pusher member
having main driving and holdback faces. At a normal spacing between
the power and carrier tracks, the main driving and holdback faces
on the pusher member are engageable with the main driving dog of a
carrier and the pusher member is movable to a nondriving position
in response to engagement with a stop or with the auxiliary driving
dog of a preceding carrier. At a reduced track spacing, the pusher
member is movable to a position of positive driving engagement with
the main carrier driving dog, or alternately, the auxiliary driving
face of the pusher unit is engageable with the auxiliary driving
dog of a carrier.
Inventors: |
Lempio; George D. (Detroit,
MI) |
Assignee: |
Jervis B. Webb Company
(N/A)
|
Family
ID: |
25206627 |
Appl.
No.: |
04/811,469 |
Filed: |
March 28, 1969 |
Current U.S.
Class: |
104/172.4 |
Current CPC
Class: |
B61B
10/025 (20130101) |
Current International
Class: |
B61B
10/02 (20060101); B61B 10/00 (20060101); B65g
017/42 () |
Field of
Search: |
;104/172,178 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: La Point; Arthur L.
Assistant Examiner: Saifer; Robert W.
Claims
I claim:
1. In a conveyor of the type having a carrier track, a power track
mounted in spaced relation with the carrier track, a carrier on the
carrier track provided with a driving dog engageable by a pusher
unit of a propelling member supported on the power track for
imparting forwarding movement to the carrier; the improvement
wherein:
the pusher unit includes a main driving face and an auxiliary
driving face, the main driving face and a camming portion being
formed on a pusher member;
means mounting the pusher member for movement between an engaged
and a disengaged position of the main driving face relative to a
carrier driving dog at a normal spacing between the carrier and
power tracks in response to contact of the camming portion with an
object in the path of pusher travel;
and an auxiliary driving dog on the carrier, said auxiliary driving
dog being engageable by said camming portion of the pusher member
at said normal spacing and by said auxiliary driving face of the
pusher unit at a spacing between the carrier and power tracks which
is less than said normal spacing.
2. A conveyor according to claim 1 wherein the carrier is provided
with a pusher member retaining cam adapted to hold the pusher
member in said disengaged position in response to contact between
the pusher member camming portion and said retaining cam at said
normal track spacing, and wherein said retaining cam is formed with
said auxiliary carrier driving dog.
3. A conveyor according to claim 2 wherein the carrier includes a
main holdback dog adapted to be abuttingly engaged by the auxiliary
driving dog of an immediately preceding overtaken carrier.
4. A conveyor according to claim 3 wherein the carrier includes a
guide surface adapted to be overlapped by the retaining cam of a
preceding overtaken carrier.
5. A conveyor according to claim 1 wherein said pusher unit
includes a pusher bracket, structurally united with the propelling
member;
means connecting the pusher member to the pusher bracket for
limited pivotal movement between a retracted and an extended
position relative to the propelling member, the pusher member being
biased to the extended position;
and the pusher member extending rearwardly from the pivot means
with respect to the direction of forwarding carrier movement and
having said main driving face and a holdback face, said driving and
holdback faces being spaced longitudinally of the pusher member,
and wherein said auxiliary driving face of the pusher unit is
located forwardly of the main driving face.
6. A conveyor according to claim 5 wherein said auxiliary driving
face is formed by a portion of the pusher bracket projecting
forwardly of the pivot means.
7. A conveyor according to claim 5 wherein said auxiliary driving
face is formed at least in part on a portion of the pusher member
projecting forwardly of said pivot means.
8. A conveyor according to claim 5 wherein the holdback face on the
pusher member in the retracted position thereof extends closer to
the carrier track than said main driving face.
9. A conveyor according to claim 8 wherein the carrier includes a
main holdback dog and a secondary holdback dog located forwardly
thereof and projecting a lesser distance toward the power tracks,
said secondary holdback dog being engageable with the holdback face
of the pusher member at a spacing between the carrier and power
tracks less than said normal spacing.
10. A conveyor according to claim 1 wherein the pusher unit
includes a pusher bracket structurally united with the propelling
member and carrying pivot means to which the pusher member is
connected, and stop means on the pusher member and bracket limiting
movement of the pusher member in directions toward and away from
the propelling member.
11. A conveyor according to claim 10 wherein the pusher bracket
includes a portion projecting forwardly of said pivot means, said
auxiliary driving face of the pusher unit being formed on said
forwardly projecting bracket portion.
12. A conveyor according to claim 1 wherein the carrier includes a
main holdback dog having a portion which extends transversely of
the path of travel a distance greater than does the auxiliary
driving dog, a stop plate mounted adjacent the carrier track at a
location where the carrier and power tracks are arranged at said
normal spacing for movement to and from a stopping position, the
stop plate in stopping position being abuttingly engageable only by
said transversely extending portion of the main holdback dog, and a
lateral extension on the camming portion of the pusher member
engageable with the stop plate in the stopping position
thereof.
13. A conveyor according to claim 12 wherein the auxiliary driving
dog is combined with a pusher-retaining cam, the pusher-retaining
cam having means at the forward end thereof for imparting movement
to the stop plate away from the stopping position in the event of
engagement therewith.
14. In a power and free conveyor having a carrier track, a power
track arranged in spaced relation therewith and supporting a
propelling member, an improved pusher unit mounted on the
propelling member for imparting forwarding movement to a carrier on
the carrier track comprising:
a bracket member adapted to be secured to the propelling
member;
a pusher member having a main driving face, a holdback face and a
camming portion in advance of the holdback face;
means connecting the pusher member to the bracket member for
limited pivotal movement between a retracted and an extended
position relative to the propelling member, the pusher member
projecting rearwardly from the pivotal axis of the connecting means
with reference to the direction of forwarding movement and said
camming portion assuming an acute angle to the longitudinal center
line of the propelling member when the pusher member is in said
extended position;
and an auxiliary driving face on one of the puser and bracket
members, the auxiliary driving face being located forwardly of the
main driving face and at a lesser distance from the propelling
member than the main driving face when the pusher member is in said
extended position.
15. An improved pusher unit as set forth in claim 14 wherein said
auxiliary driving face is formed on a portion of the bracket member
which projects forwardly of the pusher member.
16. An improved pusher unit as set forth in claim 14 wherein the
holdback face of the pusher member projects from the propelling
member a distance greater than the main driving face when the
pusher member is in said retracted position.
17. In a power and free conveyor having a carrier track, a power
track arranged in spaced relation therewith and supporting a
propelling member equipped with pushers each movable between
extended and retracted positions relative to the propelling member
in response to contact with an object in the path of pusher travel,
an improved construction for controlling movement of a carrier on
the carrier track comprising main driving and holdback dogs rigidly
mounted at the front of the carrier and projecting toward the power
track, a secondary holdback dog forwardly of and projecting a
lesser distance toward the power track than the main holdback dog,
each pusher having driving and holdback faces which overlap the
main driving and holdback dogs of the carrier at a normal spacing
between the carrier and power tracks and which overlap the main
driving and secondary holdback dogs of the carrier with decreased
longitudinal clearance at a spacing between the carrier and power
tracks less than said normal spacing.
18. A power and free conveyor according to claim 17 wherein a
portion of the carrier intermediate the driving and holdback dogs
supports a pusher in a retracted position at said lesser track
spacing, and means limiting further retracting movement of said
pusher to an amount less than said overlap.
Description
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to improvements in power and free conveyors
of the type in which carriers may be releasably propelled for
stopping and accumulation, positively propelled, and transferred
between power lines.
2. Description of the Prior Art
A conventional power and free conveyor includes a track-supported
endless propelling member with pushers thereon, hereinafter
referred to as the power line, mounted adjacent to a track on which
carriers are supported, each carrier having a driving dog
projecting toward the power line and engageable by a pusher
thereof. Conveyor systems of this type may have a network of
carrier tracks and a plurality of power lines with requirements for
the transfer of carriers between power lines, the stopping and
accumulation of carriers along a power line, and the propulsion of
carriers along vertical curves with a positive connection between a
pusher and a carrier.
Two types of construction have been used or proposed to satisfy the
requirement for the stopping and accumulation of carriers. In one
of these types, the carrier is provided with a driving dog which is
movable between driving and nondriving positions relative to a
pusher, as shown in U.S. Pat. No. 3,044,416. The second type of
construction employs a pusher which is movable between such
positions relative to a carrier driving dog either by a cam on the
power line as shown in U.S. Pat. No. 3,099,228 or by a cam on the
carrier as found in German Pat. No. 1,143,499 and U.S. Pats. Nos.
3,418,948 and 3,418,949.
The present invention answers a need for a simple, inexpensive
conveyor construction of the movable pusher type which will not
only permit the stopping and accumulation of carriers but which
will also meet the other conveyor system requirements for the
positive propulsion of carriers and the transfer of carriers
between power lines.
SUMMARY OF THE INVENTION
The invention provides new combinations of elements on the
propelling member and carriers of a power and free conveyor which
function in different ways at varying spacings between the power
and carrier tracks to satisfy the requirements mentioned above. On
the propelling member these elements are formed on longitudinally
spaced pusher units, each having an auxiliary driving face and a
pusher member provided with main driving and holdback faces, the
pusher member being mounted for limited movement relative to the
propelling member between retracted and extended positions and
being gravity biased to the latter position. The auxiliary driving
face is formed on a portion of the pusher unit which is forwardly
of the main driving and holdback faces on the pusher member and
which is closer to the propelling member than are the main driving
and holdback faces when the pusher member is in its extended
position.
On each carrier the elements are found on relatively fixed members
projecting toward the power track at the front and rear ends of the
carrier. The front member includes a main driving dog, a main
holdback dog, a secondary holdback dog located forwardly of the
main holdback dog and projecting a lesser distance toward the power
track, and a guide surface between the two holdback dogs. The rear
member includes an auxiliary driving dog and a pusher-retaining
cam, the retaining cam having a transverse dimension less than that
of the main driving and main holdback dogs.
At a normal spacing between the power and carrier tracks, the main
driving face of the pusher member is engageable with the main
carrier driving dog and disengageable therefrom in response to
contact of the holdback portion of the pusher member with a
stopping device or with the auxiliary driving dog of a leading
carrier. The holdback portion of the pusher has a camming action to
produce this disengaging pusher movement, and the pusher-retaining
cam on a carrier prevents reengagement of the auxiliary driving dog
by the main driving face of the pusher. Thus a carrier can be
stopped, and any following carrier which overtakes a stopped
carrier will also stop and accumulate. In this stopping and
accumulation of carriers, the main holdback dog serves as an
abutment engaged by the stopping device or by the auxiliary driving
dog of a leading carrier.
At a decreased spacing between the power and carrier tracks, the
auxiliary driving dog of a carrier is engageable by the auxiliary
driving face of a pusher unit to advance the carrier through a
transfer zone.
Also at a decreased track spacing, a pusher member which is in
engagement with a main carrier driving dog is moved thereby toward
the retracted pusher position, and the secondary holdback dog of
the carrier is moved into overlapping relation with the holdback
face of the pusher member. This places the pusher member in
nonreleasable engagement with the carrier, reduces the extent of
relative longitudinal movement possible between the carrier and the
pusher member, and results in positive carrier propulsion.
Other features and advantages of the invention will appear from the
description to follow of the embodiments disclosed in the
accompanying drawings.
DESCRIPTION OF THE DRAWINGS
FIG. 1 is a side elevation of a portion of a power and free
conveyor of the invention, illustrating the propulsion, stopping
and accumulation of carriers;
FIG. 2 is a sectional elevation, showing a stop, taken as indicated
by the line 2-2 of FIG. 3;
FIG. 3 is a plan view, partly in section, of the construction of
FIG. 2;
FIG. 4 is a side elevation showing the positive propulsion of a
carrier at a reduced spacing between the power and carrier
tracks;
FIG. 5 is a side elevation similar to FIG. 4 but illustrating the
propulsion of a carrier by engagement of an auxiliary pusher with a
supplementary carrier driving dog; and,
FIGS. 6 and 7 are fragmentary side elevations showing the carrier
propelling and accumulating action and an alternate form of pusher
unit.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
Referring to FIGS. 1, 2 and 6, the power line consists of a track
10, of the enclosed type, supporting a propelling member 12 which
is formed of alternate pairs of links 13 carrying a pair of
supporting wheels 14 on a horizontal axis 15, and pairs of links 16
carrying a guide wheel 17 on a vertical axis 18, the links 13 and
16 being connected by pins 19. The supporting wheels 14 engage the
lower flanges 20 of the track 10. Pusher units 22 (FIGS. 1, 4 &
5) are connected to the propelling member 12 at desired intervals,
and the propelling member 12 is driven in the direction of the
arrow 21 by a conventional drive unit (not shown).
Each pusher unit 22 is composed of a bracket 23 secured to the
lower one of a pair of the links 16, and a pusher member 24 mounted
on a pivot pin 25 carried by the bracket 23. The bracket 23 is a
platelike member having a mounting pad 26 conforming to a portion
of the surface of the link 16 and formed by laterally extending
flanges, a rearwardly projecting tongue 27, and an enlarged portion
28 extending forwardly of the pusher member 24 and forming an
auxiliary driving face. The pusher member 24 has a pair of side
portions 30 forming a clevis end which straddles the bracket 23 and
receives the pivot pin 25, the side portions being joined by a
transverse web 31 underlying the bracket and by an upper web 32
overlying the bracket tongue 27. The pusher member is free to pivot
about the axis of the pin 25 and is thus mounted for limited
movement relative to the propelling member 12 between the retracted
position illustrated in FIG. 4 and the extended position of FIG. 5,
being biased to the latter position by gravity.
A main driving face 34 and a holdback face 35 are formed on the
pusher member 24, the main driving face being located farther from
the pivot pin 25 than is the holdback face 35, and being inclined
forwardly rather than extending in tangential relation to the axis
of the pivot pin. The portions of the pusher member on which the
driving face 34 and holdback face 35 are formed are transversely
wider than the clevis portion 30, as shown in FIG. 2 and each of
these driving and holdback portions have beveled side edges 37. The
outer transverse surface of the web 36 on the holdback portion
extends at an acute angle to the longitudinal centerline of the
propelling member when the pusher member 24 is in extended position
so as to provide a camming action urging the pusher member to
retracted position in the event of contact of the holdback portion
with an object in its path of travel.
Below the power track 10 are a pair of transversely spaced channel
section track members 39 and 40 which form a carrier track suitably
supported from the power track 10. Only the carrier track member 40
is shown in FIG. 1 in order to more clearly illustrate the
construction of a carrier 42. This carrier 42 is of the multiple
trolley type, having a front trolley 44 and a rear trolley 45
connected by a load bar 46, the trolleys being similar but not
identical in construction.
Each of the trolleys 44 and 45 (FIGS. 1 and 2) has pairs of front
and rear wheels 47, each pair of wheels being mounted on an axle 48
which extends through apertures in a pair of plates 49 and in a
body member 50 mounted between the plates as shown in FIG. 2. Guide
rollers 52 are mounted on the plates which are transversely spaced
at their lower portion to receive a connector 53 which is secured
between the plates on a pivot 54 and which pivotally suspends a
load bar-supporting bracket 55.
The trolley body member 50 may take one of three forms. On the
front trolley 44, (FIGS. 6 and 7) the body member 50 includes a
portion 56 projecting upwardly towards the power track 10 and
having a main driving dog 58, a main holdback dog 59, a horizontal
guide surface 60, and a secondary holdback dog 61. As shown in
FIGS. 2 and 3, the upper extremity of the portion 56 is enlarged
transversely and formed with downwardly beveled sides 57. On the
rear trolley 45, the body member 50 includes an upwardly projecting
portion 62 which includes a retaining cam 63, a supplementary
driving dog 64, a guiding bevel 65 and a forward plow 66, best
shown in FIG. 3. The third form of the body member 50 is a
combination of the first and second forms described, including both
the upwardly projecting portion 56 of the front trolley 44 and the
upwardly projecting portion 62 of the rear trolley 45; and this
third form is used for single trolley carriers or for the front
trolley of multiple trolley carriers in installations where
carriers are at some places transferred from in-line travel on a
single track, as shown, to side-by-side travel on a pair of
parallel tracks.
An alternate construction of a pusher unit appears in FIGS. 6 and
7, this unit also consisting of a bracket 70 and a pusher member 71
mounted on a pivot 72. The bracket 70 is formed by a pair of
parallel plates secured to a line, 16 of the propelling member, the
plates being joined by the pivot 72 and by a stop pin 73. The
pusher member 71 is mounted between the bracket plates and has a
driving face 74, a holdback face 75, a recess 76 receiving the stop
pin 73, and a front end 78 which projects forwardly of the pivot
72, at least as far as does the part of the bracket around the
pivot, and forms an auxiliary driving face.
The foregoing components, together with changes in spacing between
the power and carrier tracks, coact to provide all types of carrier
movement and propulsion which may be required in a power and free
system, namely, the stopping and accumulation of carriers, the
transfer of carriers under power, and the positive propelling of
carriers.
Stopping and accumulation of carriers are illustrated in FIGS. 1,
2, 3, 6 and 7, and for this mode of operation, the power and
carrier tracks are mounted at a normal spacing as indicated by the
dimension 80. At this track spacing, and with a pusher member 24 or
71 in the extended position to which it is biased by gravity, the
main driving dog 58 of the carrier is engageable by the main
driving face 34 or 74 of a pusher member, and the holdback dog 59
of the carrier is overlapped by the holdback face 35 or 75 of the
pusher member, although the extent of overlap is less than that
between the pusher member and driving dog. The holdback or camming
portion 36 of the pusher member also extends into an interference
position relative to the main driving dog 58, the auxiliary driving
dog 64 and the retaining cam 63.
The pivotal mounting of the pusher member permits movement thereof
between this engaged position relative to the carrier driving dog
58 and a disengaged position relative thereto as shown in FIGS. 2
and 7, such movement resulting from contact between the holdback
portion of a pusher member and a carrier stop plate 81 or the
auxiliary driving dog 64 of an overtaken carrier.
The stop plate 81 forms part of a stop assembly shown in FIGS. 2
and 3. This assembly includes a mounting plate 82 suitably secured
to the power track 10. A base plate 83, having an upper portion 84
and a portion 85 providing a vertically offset platform 86, is
adjustably secured to the mounting plate 82 by a pair of upstanding
screws 87 (only one of which is shown), each carrying a pair of
nuts 88. A pivot shaft 89 is supported between a pair of blocks 90
attached to the upper portion 84 of the base plate 83. The stop
plate 81 is formed by the lower flange of a "C" shaped arm 91,
having an upper portion 92 which is welded to a sleeve 93 on the
shaft 89. The arm 91 can thus be rocked on the shaft by a suitable
actuator such as the solenoid 94 mounted on the offset platform 86
of the base plate and connected to the arm 91 by a lever 95. A
bumper 96 mounted on the upper portion 84 of the base plate 83
limits outward or releasing movement of the arm 91, as indicated by
the broken line position of the arm 91 in FIG. 2. Also, a bumper 97
secured to the side of the arm 91 adjacent the power track 10
defines the operative or carrier stopping position of the arm 91
and its stop plate 81. As shown in FIG. 3, this stopping position
is one in which the stop plate 81 extends into the path of travel
of only a laterally projecting portion of the holdback dog 59 of a
carrier, and does not extend across the path of carrier travel an
amount sufficient for positive engagement by the retaining cam
portion 63 of a carrier; in fact, such positive engagement is
prevented by the plow-shaped forward portion 66 on the retaining
cam.
The stop assembly also includes an antibackup member 98 on the
lower end of an arm 99 connected to a second sleeve mounted on the
pivot shaft 89 for free rocking movement, and gravity biased to the
position shown in FIG. 3 in which the member 98 overlaps the
driving dog 58 of the carrier.
The stop assembly is mounted with the axis of the pivot shaft 89
extending at an acute angle to the longitudinal center line of the
tracks, and the stop arm 91 is secured to the sleeve 93 so that the
vertical portion of the arm 91 extends parallel to the side of the
power track 10. As a result of this angular relation of the parts,
movement of the arm 91 from carrier stopping to released position
includes a forward component of motion of the stop plate 81 for
ease of disengagement from the holdback dog 59 of a carrier. This
angulation is not employed in mounting the antibackup arm 99.
When a carrier, being propelled by a pusher unit at normal track
spacing as shown in FIG. 1, approaches a stop plate 81 which is in
stopping position, contact first occurs between the leading edge of
the stop plate and the holdback portion 36 of the pusher member 24
causing the pusher member to pivot to a position of disengagement
from the carrier driving dog 58, and to be retained in this
position by the upper surface of the stop plate as the holdback dog
59 of the carrier abuts against the leading edge of the stop 81 and
the antibackup member 98 which had been pushed aside, swings back
into overlapping relation with the carrier driving dog 58 to limit
rebounding carrier movement.
With the carrier stopped, a pusher member 24 propelling a following
carrier overtaking the stopped carrier, as indicated by the front
carrier trolley 44A shown in broken line at the left of FIG. 1, is
moved to disengaged position by the auxiliary driving dog 64 on the
rear trolley 45 and is held in this position while passing over the
retaining cam 63 of the stopped carrier. This action is similar to
that illustrated in FIG. 7 for the pusher member 71. The following
carrier is stopped by engagement of its holdback dog 59 with the
auxiliary driving dog 64 of the leading carrier, this engagement
being insured by the beveled surface 65 on the leading carrier and
the guide surface 60 on the following carrier.
The transfer of a carrier under power from a forwarding to a
receiving power line is accomplished by decreasing the spacing
between the power track of the forwarding power line and the
carrier track as illustrated in FIG. 5. At this reduced spacing
indicated by the dimension 102, the auxiliary pusher 28 formed by
the nose of the puser bracket 23 (or the auxiliary pusher 78 on the
pusher member 71 of FIG. 6 and 7) is engageable with the auxiliary
driving dog 64 of a carrier to advance the carrier into a position
where the main driving dog can be picked up by a pusher unit on the
receiving power line.
Positive propulsion of a carrier, which is preferred for traversing
vertical curves of a system, is also obtained by reducing the
spacing between the power track 10 and carrier track as shown in
FIG. 4. This reduced spacing, indicated by the dimension 104,
causes a pusher member, when engaged with the main carrier driving
dog 58, to be displaced thereby to almost the limit of retracting
movement, defined by abutment between the bracket tongue 27 and the
pusher member web 31. In this retracted position of the pusher, the
main driving face 34 thereof has increased overlapping engagement
with the carrier driving dog 58; also, the holdback face 35 of the
pusher member has increased engagement, overlapping the secondary
holdback dog 61 of the carrier and thereby decreasing the amount of
relative movement which can take place between the carrier and a
pusher unit longitudinally of the path of travel.
* * * * *