U.S. patent number 3,683,817 [Application Number 05/064,975] was granted by the patent office on 1972-08-15 for power and free conveyor system with variable length carriers.
This patent grant is currently assigned to Jervis B. Webb Company. Invention is credited to Clarence A. Dehne, Robert A. Macomber.
United States Patent |
3,683,817 |
Macomber , et al. |
August 15, 1972 |
**Please see images for:
( Certificate of Correction ) ** |
POWER AND FREE CONVEYOR SYSTEM WITH VARIABLE LENGTH CARRIERS
Abstract
A conveyor system for track supported carriers, each having a
driving dog engageable by a pusher, in which each carrier has front
and rear trolleys connected by front and rear tow bar members that
are relatively movable longitudinally of the track to extend or
reduce the length of the carrier. A latch device provides a
plurality of selectable relative positions of the tow bar members
and a latch release mounted adjacent the carrier track permits the
carrier length to be changed as desired. The length of a carrier
may be changed by installing the latch release on an inclined
section of track; or the carrier length may be adjusted as desired
by stopping one of the carrier trolleys, releasing the latch
device, and moving the other trolley by an auxiliary pushing
apparatus.
Inventors: |
Macomber; Robert A. (Novi,
MI), Dehne; Clarence A. (Farmington, MI) |
Assignee: |
Jervis B. Webb Company
(N/A)
|
Family
ID: |
22059512 |
Appl.
No.: |
05/064,975 |
Filed: |
August 19, 1970 |
Current U.S.
Class: |
104/89;
104/172.4 |
Current CPC
Class: |
B61B
10/022 (20130101) |
Current International
Class: |
B61B
10/02 (20060101); B61B 10/00 (20060101); B61b
003/00 () |
Field of
Search: |
;104/172S,178,89,96
;105/393 ;280/34T ;287/58CT |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: La Point; Arthur L.
Assistant Examiner: Saifer; Robert
Claims
What is claimed is:
1. In a conveyor system of the type having a carrier supporting
track, a carrier including trolleys mounted on the carrier
supporting track, a propelling member supported by an adjacent
track and having a pusher engageable with a main driving dog on the
carrier, and the carrier having at least one front and one rear
trolley interconnected by a tow bar; the improvement wherein the
tow bar comprises a front member connected to the front trolley and
extending toward the rear trolley, and a rear member connected to
the rear trolley and extending toward the front trolley; means
carried by at least one of the tow bar members engaging and
supporting the other tow bar member for relative longitudinal
movement between said members whereby the length of the carrier can
be extended and reduced; and a latch device releasably connecting
the tow bar members together in one of a plurality of selectable
relative positions, the latch device including a remotely operable
latch member.
2. A conveyor system according to claim 1 wherein means for
releasing the latch device is mounted adjacent the carrier
supporting track.
3. A conveyor system according to claim 2 wherein the carrier
supporting track extends on an incline where the latch releasing
means is mounted whereby the length of the carrier is varied
automatically is response to release of the latch device.
4. A conveyor system according to claim 3 further including means
for limiting relative longitudinal movement between said tow bar
members which occurs in response to release of the latch
device.
5. A conveyor system according to claim 1 wherein the main driving
dog on the carrier is mounted rearwardly of said front trolley.
6. A conveyor system according to claim 5 further including an
upwardly inclined section in the carrier and propelling member
supporting tracks, and means mounted adjacent the carrier
supporting track for maintaining the latch device in released
condition while at least said front carrier trolley is on the
upwardly inclined section in the carrier supporting track whereby
the length of the carrier can be reduced in response to release of
the latch device.
7. A conveyor system according to claim 5 wherein the main driving
dog on the carrier is provided on a driving trolley connected to
said rear trolley.
8. A conveyor system according to claim 7 wherein the driving
trolley is located between said front and rear trolleys.
9. A conveyor system according to claim 1 wherein said front and
rear tow bar members are telescopingly arranged inner and outer
tubes, said means carried by at least one of the tow bar members
engaging and supporting the other tow bar member comprising inner
rollers carried by the inner tube engaging the inner surface of the
outer tube and outer rollers carried by the outer tube engaging the
outer surface of the inner tube.
10. A conveyor system according to claim 9 wherein the latch member
is movably mounted on the outer tube, a plurality of detents are
spaced longitudinally along the inner tube, the latch member having
a locking portion engageable with a selected detent.
11. A conveyor system according to claim 1 further including a
carrier length adjusting station having means for releasing the
latch device, and means for relatively moving the tow bar members
to a desired carrier length.
12. A conveyor system according to claim 11 wherein the latch
device comprises a plurality of longitudinally spaced detent
elements provided on one of the tow bar members, the latch member
being mounted on the other of the tow bar members for movement
between a locking and a released position relative to a detent
element, and said means for releasing the latch device includes
actuating means for moving the latch member to released
position.
13. A conveyor system according to claim 12 wherein the latch
device includes means normally retaining the latch member in
locking position, said means for releasing the latch device
including actuating means for releasing the retaining means.
14. A conveyor system according to claim 1 further including a
carrier length adjusting station comprising means for stopping one
of said front and rear carrier trolleys, means for releasing the
latch device, and apparatus mounted adjacent to the carrier
supporting track for moving the other of said front and rear
carrier trolleys to a desired carrier length.
15. A conveyor system according to claim 14 wherein the latch
member, is movably mounted on the tow bar member connected to the
stopped one of said front and rear carrier trolleys, and a
plurality of detents are spaced longitudinally along the tow bar
member connected to the other of said front and rear trolleys, the
latch member having a locking portion engageable with a selected
detent.
16. A conveyor system according to claim 1 wherein the latch device
includes a plurality of longitudinally spaced detent elements
provided on one of the tow bar members and the latch member is
mounted on the other of the tow bar members for normally biased
movement from a disengaged to an engaged position relative to a
detent element; and retaining means for releasably holding the
latch member in a disengaged position.
17. A conveyor system according to claim 16 further comprising
means for actuating the latch device mounted adjacent to the
carrier track and including means for moving the latch member to
disengaged position and means for releasing the retaining means to
permit movement of the latch member to engaged position.
18. A conveyor system according to claim 17 wherein the retaining
means is capable of locking the latch member in engaged position,
the means for actuating the latch device including means for
unlocking the retaining means prior to moving the latch member to
disengaged position.
19. A conveyor system according to claim 16 wherein the retaining
means comprises a retaining member mounted on the other of the tow
bar members for normally biased movement from a retaining to a
locking position relative to the latch member, the retaining member
in the locking and retaining positions being releasably engageable
with the latch member in the engaged and disengaged positions,
respectively.
20. A conveyor system according to claim 19 wherein the latch and
retaining members each include a follower portion, and wherein
latch and retaining member cam means are mounted adjacent the
carrier supporting track for engagement by the respective follower
portions to move the retaining member from locking position, move
the latch member from engaged to disengaged position, move the
retaining member to retaining position relative to the latch member
and release the latch and retaining members for movement to engaged
and locking position respectively.
21. A conveyor system according to claim 1 including a transfer
station at which a load is removed from the carrier having the tow
bar members in a relatively extended condition,
and means following the transfer station for reducing the length of
the unloaded carrier including means for releasing the latch
device.
22. A conveyor system according to claim 21 wherein the driving dog
on the carrier is located so as to transmit driving force to a
portion of the carrier other than and rearwardly of said front
trolley, and the means following the transfer station for reducing
the length of the unloaded carrier includes an upwardly inclined
section in the carrier and propelling member supporting tracks, the
means for releasing the latch device being operable to permit the
carrier length to be reduced at least in part by gravitational
force on the carrier produced by said upwardly inclined track
section.
23. A conveyor system according to claim 21 wherein the transfer
station is one at which a load releasably supported by connections
to forward and rearward portions of the carrier is deposited on a
receiving conveyor, and the driving dog on the carrier is
associated with the rearward portion of the carrier whereby the
forward load connection can be released while the load is being
advanced through the rearward load connection.
24. A conveyor system according to claim 23 wherein the driving dog
on the carrier is provided on a driving trolley located between
said front and rear trolleys and connected to the rear trolley.
25. A conveyor system according to claim 24 further including an
upwardly inclined section in the carrier and propelling member
tracks following the transfer station, and means for releasing the
latch device so that the carrier length is reduced at least in part
by upward movement of the front trolley on the inclined track
section.
26. A conveyor system according to claim 25 wherein the means for
releasing the latch device includes cam means mounted adjacent the
carrier track and engageable by follower means operatively
associated with the latch device.
Description
SUMMARY OF THE INVENTION
This invention relates to improvements in a conveyor system of the
type having carriers supported on a carrier track and driven by
engagement of driving dogs on the carriers by pushers of a
separately supported propelling member. The improvements of the
invention permit the length of a carrier to be automatically
extended or reduced as desired, thereby enabling the handling of a
variety of different length loads in a single system and enabling
the carrier length to be changed according to load conditions. For
example, in a system where carriers circulate between a loading
station and an unloading station, unloaded carriers being returned
for loading can be reduced in length to conserve space and then
each extended in length as required to match the next load.
In the conveyor system of the invention, a carrier has at least one
front and one rear trolley interconnected by a tow or load bar
which comprises a front member connected to the front trolley and
extending toward the rear trolley, and a rear member connected to
the rear trolley and extending toward the front trolley. These tow
bar members are supported one upon the other for relative
longitudinal movement so that the length of the carrier can be
extended and reduced. A latch device releasably connects the tow
bar members together in one of a plurality of selectable relative
positions.
This latch device is releasable by means mounted adjacent the
carrier supported track, and a change in the length of a carrier
can be obtained either by installing the latch releasing means on
an inclined section of the carrier supporting track, or by
employing in combination with the latch releasing means an
auxiliary pushing mechanism capable of engaging and moving one part
of the carrier relative to another part thereof to produce relative
longitudinal movement between the tow bar members. In the preferred
embodiment disclosed herein, the carrier driving dog is mounted on
a driving trolley located rearwardly of the front carrier trolley,
and latch releasing means are installed on an upwardly inclined
section of the carrier track following an unloading station with
the result that all carriers passing this latch releasing means are
automatically reduced to a minimum length for return to a loading
station. In advance of the loading station, means are provided for
adjusting the length of the carrier as desired, and consist of the
combination of a stop which arrests forward movement of the driving
trolley and rear tow bar member, a latch releasing means, and
auxiliary pusher apparatus which engages and moves the forward
trolley and load bar a desired distance relative to the rear
trolley and load bar.
Preferably, the latch device consists of a latch member carried by
one of the tow bar members and having a latch portion engageable
with one of a plurality of detents spaced longitudinally along the
other tow bar member, and a latch retainer capable of engaging and
holding the latch member in both the locking and released positions
of the latter. The latch and latch retainer members are operable by
cams mounted adjacent to the carrier track.
Other features and advantages of the invention will appear from the
description to follow of the representative embodiment thereof
disclosed in the accompanying drawings.
DESCRIPTION OF THE DRAWINGS
FIG. 1 is a side elevation showing a conveyor and carrier
constructed in accordance with the invention;
FIG. 2 is an enlarged sectional elevation taken as indicated by the
line 2--2 of FIG. 1 and including a latch device on the carrier and
latch releasing means mounted adjacent to the path of carrier
travel;
FIG. 3 is an enlarged elevation of the front portion of the carrier
of FIG. 1
FIG. 4 is a sectional plan view taken as indicated by the line 4--4
of FIG. 3 and including a fragmentary showing of apparatus for
changing the length of the carrier;
FIG. 5 is an enlarged elevation of the tow bar portion of the
carrier of FIG. 1;
FIG. 6 is an enlarged sectional detail taken on the line 6--6 of
FIG. 5;
FIG. 7 is an enlarged sectional detail taken on the line 7--7 of
FIG. 5;
FIG. 8 is an enlarged sectional detail of the latch device and
releasing means of FIG. 2, taken as indicated by the line 8--8 of
FIG. 5;
FIG. 9 is a detailed elevation of a releasing means of FIG. 2;
FIG. 10 is a plan view of the structure shown in FIG. 9;
FIG. 11 is a schematic elevation illustrating a load transfer
station and a carrier length reducing operation; and
FIG. 12 is a schematic plan view illustrating carrier length
reducing and extending operations.
DESCRIPTION OF THE PREFERRED EMBODIMENT
Referring first to FIGS. 1-4, the type of conveyor system to which
the improvements of the invention relate includes an upper power
track 10 for trolleys 12 which are connected to an endless
propelling member or chain 13, driven by conventional driving
means, not shown. Mounted below the power track 10, by hangars 14,
is a carrier supporting track 16 formed by a pair of channel
section members 17. A carrier 18 supported on the track 16 includes
a driving trolley 20 having a holdback dog 23 and a driving dog 21
engageable by a pusher 22 secured to either the propelling chain 13
or to one of the chain supporting trolleys 12, as shown in FIG. 1.
The driving trolley 20 may be of the type disclosed in U.S. Pat.
No. 3,044,416 in which the driving dog 21 is moveable between
driving and non-driving positions relative to a pusher 22, so that
carriers may be stopped as desired throughout the system. A
construction for a carrier stop for use with a driving trolley of
this type is disclosed in U.S. 991 Pat. No. 3,229,645.
The carrier 18 illustrated is designed to handle a relatively long,
heavy load 24, such as a vehicle chassis, and includes a front
trolley assembly 26 and a rear trolley assembly 27. Each of these
assemblies have a pair of load supporting trolleys 28, and the
driving trolley 20 is connected to the rear trolley assembly 27 by
a towing link 30. This arrangement of trolleys is illustrative
only. With regard to the front and rear trolley assemblies 26 and
27, these could each consist of merely a single trolley under
lighter load requirements, and, with respect to the driving trolley
20, in many cases it will also function as a load carrying trolley
and will usually be located at the leading end of the carrier.
Certain advantages to be described hereinafter, are obtainable in
the present invention when the driving trolley 20 and the driving
dog 21 are associated with the rear trolley or trolley assembly 27
of the carrier, but it is considered within the scope of the
invention to employ a driving trolley as a forward load carrying
trolley of the carrier or as a propelling unit connected to such a
forward load carrying trolley.
With respect to trolleys, then, the essential elements of a carrier
for use in a conveyor system according to the invention include at
least one front trolley, one rear trolley and a driving dog
associated with either of these trolleys.
FIGS. 2-4 show the construction of the front trolley assembly 26,
which is substantially duplicated for the rear trolley assembly 27.
A shaft 32 having a collar 33 adjacent the lower end thereof is
connected to the body of each of the pair of trolleys 28 by a
horizontal pivot pin 34, and a sleeve 35 is rotatably mounted on
each shaft 32, a thrust bearing 36 being employed between the
collar 33 and sleeve 35. A pair of longitudinally extending load
beams 37 are connected to the pair of sleeves 35, as best shown in
FIG. 4, and to a central load supporting sleeve 38. The sleeve 38
rotatably supports a vertical shaft 40 which is secured to a pair
of transversely extending load bars 42 and is connected to a hangar
44 by a transverse pivot 45. A collar 46 fastened to the bars 42
engages a bearing 47 at the upper end of the sleeve 38. Load
carrying attachments or hooks 50 are each secured by a chain 51 to
a bracket 52 mounted on the bars 42.
The front and rear trolley assemblies 26 and 27 are interconnected
by a tow bar 54 composed of a front tubular member 55 which is
connected to the hangar 44 of the front trolley assembly 26 and
extends toward the rear trolley assembly, and a rear tubular member
56 of larger diameter which is connected to the hangar 44 of the
rear trolley assembly 27 and extends toward the front trolley
assembly.
Details of the construction of the tow bar 54 are shown in FIGS.
5-7. The front tow bar member 55 and rear tow bar member 56 are
supported one upon the other for relative longitudinal telescoping
movement by means which include a circumferentially spaced cluster
of rollers 58, shown in FIG. 6, each mounted on a bracket 59
carried by the rear and outer tow bar member 56 and engaging the
surface of the front and inner tow bar member 55; and a second set
of rollers 60, shown in FIG. 7, mounted on the end of the front tow
bar member 55 and engaging the internal surface of the rear tow bar
member 56. The roller set 60 consists of a bracket member 61
mounting a roller 62 and a roller 63 on an axis normal to the axis
of the roller 62.
THe tow bar members 55 and 56 are releasably connected together in
one of a plurality of selectable positions by a latch device 66,
best shown in FIGS. 2 and 8. This latch device includes a latch
member 67 having a locking portion 68 projecting through an
aperture 69 in the tow bar member 56 and engageable in one of a
plurality of detents 70 provided at suitable intervals on the front
tow bar member 55; and, a latch retaining member 71 having a latch
72 engageable in a notch 73 or 74 in the latch member 67. A pair of
parallel plates 76 and 77 (FIG. 5) are secured to the outer tow bar
member 56 and form a bracket to which the latch member 67 is
secured by a pivot 78 and the retaining member 71 by a pivot 79.
The latch member 67 includes a laterally extending arm portion 80
carrying a roller follower 81, and this arm portion 80 with
relation to the latch member pivot 78 acts as a counterweight
normally biasing the latch member 67 to the full line position
shown in FIG. 2 and FIG. 8 in which the locking portion 68 engages
a detent 70 on the tow bar member 55. The retaining member 71 also
includes a laterally extending arm 82 equipped with a roller
follower 83, but the portion 84 of the retaining member, on the
side of the pivot 79 opposite the arm 82, is formed with sufficient
mass to act as a counterweight, overcoming the mass of the arm 82
and biasing the retaining member to a position in which the latch
72 on the retaining member engages one of the notches 73 or 74 in
the latch member 67. In the full line or locked position of the
members shown in FIGS. 2 and 8, the latch 72 of the retaining
member engages the notch 73 of the latch member and locks the latch
member in this position.
Means for releasing the latch device are mounted adjacent the
carrier supporting track members 17 at any desired location in the
conveyor system, and are illustrated in FIGS. 2 and 8-10. The
releasing means includes a cam 86 shown at the left side of FIGS. 2
and 8 capable of moving the latch member 67 from the locked
position shown in full line toward a released position, as shown in
broken line in FIG. 8, and a cam 88 at the right hand side of FIGS.
2 and 8, capable of moving the retaining member 71 from the locked
position shown in full line toward a released position as shown in
broken line in FIG. 8.
FIGS. 9 and 10 illustrate the construction and mounting of the cam
88, consisting of suitable bracket structure 90 secured to one of
the carrier track members 17; the cam 88, as shown in FIG. 10,
including an actuating portion 91 extending angularly to the track
17 and a retaining portion 92 extending parallel thereto. The
construction and mounting of the cam 86 are similar to the cam 88.
However it will be understood that the retaining member cam 88 is
positioned along the path of carrier travel in advance of the
locking member cam 86 so that the retaining member 71 is moved to
released position prior to the locking member 67. Also, the portion
92 of the retaining member cam 88 terminates prior to the
corresponding portion of the locking member cam 86 so that the
retaining member 71 is released from the cam 88 and the latch 72
falls into engagement with the notch 74 on the latch member 67,
holding the latch member in released position. This relationship
between the cams 86 and 88 is shown in FIG. 12 and will be further
described.
FIGS. 11 and 12 illustrate representative features and advantages
obtainable from the invention in a conveyor system. In FIG. 11, the
load 24 is transferred from the carrier 18 of the overhead power
and free conveyor, traveling in the direction indicated by the
arrow 94, to a schematically illustrated flat top conveyor 95
moving in the same direction as indicated by the arrow 96.
Approaching the transfer zone, the tracks 10 and 16 of the overhead
conveyor are gradually inclined downwardly to a load transfer level
indicated by the reference 97 at which the front end of the load 24
is supported on the conveyor 95 and the hooks 50 (FIG. 1)
supporting the front end of the load can be manually disengaged
therefrom. The rear end of the load is still suspended from the
carrier 18 which is propelled at substantially the same speed as
the conveyor 95 until the rear trolley assembly 27 of the carrier
reaches the load transfer level 97 and the load is completely
disengaged. Following the transfer level 97, the conveyor tracks 10
and 16 are inclined aburptly upwardly as indicated by the reference
98 to return the carrier to a clearance height. By propelling the
carrier from the driving trolley 20 through the rear trolley
assembly 27, the carrier can be cleared from the transfer area in
less time and in less space. The front end of the carrier can
commence moving to a clearance relation up the incline 98 (which
changes the rate of movement relative to the conveyor 95)
immediately after the load has been disconnected, while the load
continues to be advanced by the rear trolley assembly 27 at a
proper relative rate for transfer to the conveyor 95.
An empty carrier 18 traveling up the inclined section 98 may be
immediately transferred to another power conveyor, indicated by the
upper track 10', for return at a different rate of travel to a
carrier storage or loading area.
Empty carriers may be automatically reduced to a minimum length by
providing latch device releasing cams 86 and 88 along the upwardly
inclined section 98, as shown. These releasing cams are arranged as
schematically indicated at the right hand portion of FIG. 12. Cam
88 engaged by the latch releasing member 71 is located in advance
of the cam 86 engaged by the latch member 67 with relation to the
direction of travel 94. Consequently, the latch retaining member 71
first engages the cam 88 and is moved to a released position
relative to the latch member 67 which then engages the cam 86 and
is in turn moved to released position relative to a detent 70 on
the carrier front tow bar 55. The latch retaining member 71
disengages from the cam 88 while the latch member 67 is still
engaged with the cam 86, and hence the retaining member 71 returns
from a full released position to a position in which the latch
element 72 thereon engages the notch 74 on the latch member 67, and
when the latch member 67 then disengages from the cam 86, the
retaining member 71 holds the latch member in released
position.
The combination of gravity and the forward motion of the rear
trolley assembly 27 produces an inward telescoping relative
movement between the tow bars 55 and 56 until the minimum carrier
length is reached as defined by abutment between rear tow bar 56
and front hangar 44, or other suitable movement limiting means. The
latch retaining member 71 then engages a second cam 88' shown in
FIG. 12, the latch element 72 is moved out of engagement with the
notch 74 on the latch member 67 which then returns to latched
position, and the retaining member is then returned to locking
position.
Essential elements of a carrier length adjusting station are
schematically shown in the left hand portion of FIG. 12, and it
will be assumed that each carrier, prior to arriving at this
station, has been reduced to minimum length as just described.
THese components include a carrier stop 100 having a stop plate 101
capable of depressing the carrier driving dog 21 and being abutted
by a hold back dog 23 on the driving trolley 20 as more fully
described in U.S. Pat. NO. 3,229,645 3,229,645; a retaining member
cam 88 and a latch member cam 86 selectively positionable by
actuating cylinders 102 and 103; and, auxiliary pusher apparatus
104 consisting of a suitably driven propelling member 105 equipped
with one or more one-way pushers 106.
If the length of a carrier is to be changed, the stop 100 is
actuated, moving the stop plate 101 to blocking position as shown,
and the driving trolley 20 of the carrier is stopped with the rear
trolley assembly 27 and rear tow bar 56 in a position at which the
latch is released by the cams 88 and 86 which also have been
positioned to be engaged by the latch retaining member 71 and latch
member 67 respectively. In this position of the carrier, the
transverse load bars 42 on the front trolley assembly 26 can be
engaged by a pusher 106, when the auxiliary pusher apparatus 104 is
activated, to advance the front trolley assembly 26 and front load
bar 55 the proper distance for the length of carrier desired. The
actuating cylinders 102 and 103 are then energized to release the
cams 86 and 88 and lock the carrier tow bars 55 and 56 together.
The stop plate 101 is then retracted and the carrier is picked up
by the next advancing pusher 22.
Operation of these various components of the length adjusting
station are preferably controlled automatically, as in response to
the setting of the desired length for a carrier, by a system of
control elements which has not been shown, as such a system is
considered to be within the capability of those skilled in the
control art.
* * * * *