Drive unit for transport trolley having plastic center link and drive dog covering for noise reduction

The present invention intends to prevent generation of metallic noise when both longitudinal sides of the chain supporting trolley (22) installed to the center link (19) of the chain collide against the ends of the adjoining side links (20a, 20b, 25) when the driving chains (18) which comprise linkchains in which a center link (19) whose plane shape is an elongated ring and a pair of top and bottom side links (20a, 20b, 25) are linked alternately become loose. The present invention comprises a rib (32) installed to the center link (19) at the longitudinal center, vertically notched grooves (27c, 28c, 33), in which the rib (32) of the center link is fitted, provided to the vertical portion (27a, 28a) penetrating the center link (19) of a pair of left and right trolley units (27, 28) composing the chain supporting trolley (22) and to a plate type spacer (29) which intervenes between both vertical portions (27a, 28a) and is made of plastics, and a portion of both front and rear sides of the said plate shape spacer (29), which at least adjoins the ends of the side links (20a, 20b, 25), protruded longitudinally outward from the vertical portion (27a, 28a) of each trolley unit.

FIELD OF THE INVENTION 
The present invention relates to a drive unit for propelling a transport 
trolley of a conveyor system. 
BACKGROUND OF THE INVENTION 
The type of drive unit for transport trolley with which this invention is 
concerned employs a driving chain formed by alternately linking a center 
link having an elongated annular profile, with top and bottom links 
attached to both ends of the center link with connecting pins. A plate 
shape spacer intervenes between vertical portions which penetrate the 
center link of both trolley units, and couplings link all of these three 
with each other. 
The transport equipment which utilizes this kind of drive unit can be 
classified into two broad categories: the overhead conveyor type in which 
the travel route of the chain supporting trolley is located above the 
travel route of the transport trolley, and the floor conveyor type in 
which the travel route of the transport trolley is located above the 
travel route of the chain supporting trolley. In the overhead type of 
conveyor transport equipment the drive chains are hung from a chain 
supporting trolley. A pusher is used for the bottom side link at 
appropriate intervals. A chain supporting trolley is generally linked to 
each of the center links positioned with the pusher. A driven dog of the 
transport trolley is pushed by the pusher and an antirunaway piece is 
installed close after the pusher. This antirunaway piece is vertically 
rockably pivoted to enable passing of the pusher thereover. In the floor 
type of conveyor transport equipment, it is common to install the pusher 
so that it protrudes upwardly from the lower disposed drive chains or the 
chain supporting trolley, and the driven dog and the antirunaway piece are 
installed similarly to close of the overhead type conveyor but to the 
lower side of the transport trolley. 
In the transport trolley drive unit of the above-mentioned configuration, a 
vertical connecting pin connects the center link of the driving chain with 
the top and bottom links. The vertical pin penetrates the elongated 
annular center link to be longitudinally rockable, causing the chain 
supporting trolley installed to the center link and top and bottom links 
located on both the front and the rear to approach each other horizontally 
and the opposite surfaces to collide with each other. Because these chain 
supporting trolleys and the links are made of metal, collision of the two 
results in a loud metallic noise. 
The other surface of the antirunaway piece is stricken by the pusher right 
before the pusher impacts against, and starts to push, the driven dog. 
Upon contact with the pusher the antirunaway piece tilts allowing the 
pusher to pass thereover and then the antirunaway piece falls backward 
returning to its normal position. When the pusher impacts against the 
antirunaway piece a loud metallic noise is generated. 
After the antirunaway piece is tilted forwardly by the pusher the 
antirunaway piece recovers its original position but then the contacted 
surface of the antirunaway piece collides against a tilt stopper surface 
on the side in which the antirunaway piece is pivoted. This results in 
another loud metallic noise that is similar to the noise when the pusher 
collides against the driven dog. 
These loud metallic changing and screeching noises are very disturbing and 
substantially degrade working conditions in the area. 
DESCRIPTION OF THE INVENTION 
The present invention solves the above-mentioned problems of this type of 
drive units for transport trolleys. It greatly reduces the noise generated 
by the side of the chain supporting trolley colliding against the edge of 
the side link when the driving chain becomes loose. 
It also reduces noises generated when an antirunaway piece slides against 
the pusher or the driven dog or when the antirunaway piece is tilted and 
also when it recovers its original position. 
It also reduces the noise generated when the pusher collides with against 
the driven dog. 
Accordingly, in a drive unit for a transport trolley for propelling a 
transport trolley by engagement of a pusher on a driving chain with a 
driven dog of the transport trolley, wherein the driving chain is 
supported from a chain guiding rail by chain supporting trolleys, the 
driving chain having center links of an elongated annular shape with an 
interior space, and top, bottom, and bottom pusher links each attached 
with connecting pins from the center links, the chain supporting trolley 
having right and left trolley units each with upper ends having wheels 
thereon, and each with lower ends for insertion into the interior space of 
a center link of the driving chain, a plate shaped spacer of the driving 
chain disposed between the right and left trolley units and bound together 
with fastening means, the lower ends of the right and left trolley units 
having recesses thereon for accommodating a center link therein, the 
improvement of the invention which comprises a rib extending through the 
interior space of the center link, an open groove each in the respective 
lower ends of the right and left trolley units for accommodating said rib 
therein, the plate shaped spacer having ends and longitudinal edges, said 
spacer being made of a synthetic material and having a vertical groove 
open to one end thereof for accommodating said rib therein, and the 
longitudinal edges of the spacer project outwardly from between the right 
and left trolley units. 
The open direction of the vertical groove of the plate shaped spacer is 
opposite to the open direction of the open grooves in the right and left 
trolley units. The fastening means for interconnecting the right and left 
trolley units and the plate shaped spacer comprises at least two fasteners 
disposed respectively above and below the rib and the center link. 
The invention further comprises a pivotable antirunaway piece having an 
upper part and a lower part. The antirunaway piece is mounted from the 
transport trolley or the driving chain, and has an upper contact face on 
the upper part. The antirunaway piece is pivotable for permitting passing 
of the pusher or the driven dog. A first cushioning member of a synthetic 
material covering said upper contact face adapted to contact the pusher or 
the driven dog. 
The first cushioning member has a stem with a snap retaining shoulder in a 
free end with a snap retaining shoulder thereon. A cavity is provided in 
the antirunaway piece for accommodating the first cushioning member 
therein, and a hole is provided in the antirunaway piece for locking the 
stem therein. 
Provision is made for cushioned contact between the lower part of the 
antirunaway piece and a correspondingly located part of the transport 
trolley, wherein that provision comprises either (i) that the antirunaway 
piece has a second cushioning member mounted from the lower part, or (ii) 
the correspondingly located part of the transport trolley has a cushioning 
member. 
Either the second cushioning member or the cushioning member of the 
correspondingly located part, has a stem with a snap retaining shoulder in 
a free end with an snap retaining shoulder thereon. A cavity is provided 
either in the lower part of the antirunaway piece, or in the 
correspondingly located part, for accommodating the first cushioning 
member, or the cushioning member therein. A hole is provided in the part 
with the recess for locking the stem therein. 
The pusher on the bottom pusher link, or the driven dog is adapted to 
contact the pusher that has a cushioning member for cushioning contact 
between the pusher and the driven dog. 
The cushioning member is a hollow, tapering cylindrical body of a synthetic 
material and is applied over the pusher.

DETAILED DESCRIPTION OF THE INVENTION 
In the described and illustrated embodiments of the invention the overhead 
type of conveyor is shown with only the pusher being installed on the 
driving chain side. A driven dog and an antirunaway piece are installed on 
the transport trolley side. However, as explained earlier, the present 
invention can also be embodied in the floor type of conveyor in which the 
transport trolley is located above the driving chains. It is further 
possible to embody the present invention by installing a pusher and an 
antirunaway piece located before the pusher on the driving chain side and 
only a driven dog on the transport trolley side. 
In the embodiment of the present invention shown in FIG. 1 transport 
carriage 1 is guided by a pair of parallel disposed guide rails 2, and 
connects front, intermediate, and rear transport trolleys 3, 4, and 5 to 
each other with load bars 6 and 7 and mounts load hangers 9 supporting a 
conveyed load 8 from the intermediate transport trolley 4 and the rear 
transport trolley 5. A driven dog 10 is protrudingly mounted on the upper 
front part of the front transport trolley 3, an antirunaway piece 11 is 
protrudingly mounted on the upper rear part of the front transport trolley 
3. Pairs of right and left wheels of sets of front and rear wheels are 
pivotably mounted from the front transport trolley 3. Similarly, a set of 
wheels 13 are mounted from the intermediate transport trolley 4, and a set 
of wheels 14 are mounted from the rear transport trolley 5. The wheels of 
the sets 12, 13, and 14 are adapted to run within the parallel disposed 
guide rails 2. A pair of fore and aft vertical shaft clamper rollers 15, 
16, and 17 located between the parallel guide rails 2 are pivotably 
mounted respectively from the front, intermediate and rear transport 
trolleys 3, 4, and 5. A driving chain is employed in which a center link 
19 is connected to top and bottom side links 20a, 20b with a vertical 
connecting pin 21. A chain supporting trolley 22 is connected to a center 
link 19 at predetermined intervals along the length of the driving chain 
18, and is movably supported from a chain guiding rail 23. 
Periodically, special bottom links are provided in the driving chain 18. 
These have in integral pusher 24 protruding downwardly and the chain 
supporting trolley 22 is connected to the center links 19 in front and in 
rear of the side link 25. 
As shown in FIGS. 2-4 the chain supporting trolley 22 is comprised of right 
and left trolley units 27, 28 having respectively vertical portions 27a 
and 28a. Wheels 26a, 26b are pivotably mounted respectively from these 
trolley units and a plate shaped spacer 29 is intermediately installed 
between the vertical portions 27a, 28a of the two trolley units 27, 28. 
The bolt and nut combinations 30, 31 in each trolley 22 bond trolley units 
27 and 28 and the spacers 29 into a single unit. The chain guiding rail 23 
has a single cross-sectional profile as shown in FIG. 4 and the vertical 
H-shaped right and left wheels 26a, 26b of the chain supporting trolley 22 
fit into the grooves on each side of the rail 23. 
The center link 19 has an elongated annular profile. On the outer side of 
each vertical portion 27a, 28a of a chain supporting trolley 22, 
respective indentations 27b, 28b are provided, and the center link 19 fits 
into these indentations. More specifically, a reinforcing rib protrudingly 
installed on both front and rear sides outside each trolley unit 27, 28 is 
notched to form the indentations 27b and 28b. Therefore, as shown in FIG. 
3, first the vertical portion 27a of the trolley unit 27 is inserted into 
one side of the center link 19, the center link 19 is fitted into the 
indentation 27b, and then the vertical portion 28a of the trolley unit 28 
is inserted into the other side of the center link 19. Next the other side 
of the center link 19 is filled into the indentation and the plate shape 
spacer 29 is inserted between vertical portions 27a, 28a of the trolley 
units. Then the vertical portions 27a, 28a of both the trolley units and 
place shape spacer 29 between them are linked with bolt and nut 
attachments 30, 31 at the top and bottom of the center link 19, and this 
concludes the assembly of chain supporting trolley 22 and its installation 
to the center link 19 of the driving chain 18. 
As shown in FIG. 2, 5-7 a rib 32 is formed in the center link 19, at is 
elongated side so that it perpendicularly divides the interior space of 
the link into two parts. A vertical notched groove 27c, 28c is formed 
respectively in each vertical portion 27a and 28a of each trolley unit 27 
and 28. The rib 32 is fitted from the lower side center position into the 
grooves 27c and 28c. A vertical groove 33 is formed from the upper side 
center of the plate shape spacer 29 and the rib 32 is fitted into the 
groove 33. The vertical portions 27a and 28a of the trolley units are 
inserted downwardly to the center link 19, the plate shape spacer 29 is 
inserted upwardly between them. 
The width of the vertical notched groove 33 of the plate shape spacer 29 
can be made slightly narrower than the thickness of the rib 32 to bring 
both sides of the notched groove 33 in contact with two longitudinal sides 
of the rib 32. Bolt holes 27d, 27e, 28d, 28e, 34a, 34b are provided 
respectively in vertical portions 27a, 28a and the plate shape spacer 29 
for insertion of the bolt and nut combinations 30 and 31 at the top and 
the bottom. Bolt holes 27e, 28e, 24a overlap the notched grooves 27c , 
28c, 33. 
The plate shaped spacer 29 is suitably formed from a plastic such as nylon 
6. The longitudinal dimension of the spacer is greater than that of the 
vertical portions 27a and 28a so that the longitudinal edges 29a, 29b of 
the plate shape spacer 29 protrude outwardly from between the vertical 
portions 27a and 28a. Because the driving chain 18 shown in this 
embodiment is designed to have narrow intervals (chain link pitch) between 
connecting pins 21, the longitudinal dimension of the vertical space 
within the center link 19 (portions shown with 19a, 19b in FIG. 7) 
remaining on both the front and the rear of the chain supporting trolley 
22 is short when the chain supporting trolley 22 is attached to the center 
link 19. Consequently, letting the edges 29a, 29b of the plate shaped 
spacer 29 protrude longitudinally from between the vertical portion 27a, 
28a throughout the entire vertical area, prevents the vertical connecting 
pin 21 with a T-shaped head portion on both ends as shown with broken 
lines in FIG. 7, from passing into the vertical space 19a, 19b of the 
center link 19. For that reason, as also shown in FIG. 8, the notched 
concave portions 29c, 29d are provided formed at the positions adjoining 
the vertical spaces 19a, 19b of the center link 19 of the front and rear 
edges 29a, 29b of the plate shape spacer 29. 
When the chain supporting trolley 22 is installed through the center link 
19 a pair of top and bottom side links 20a, 20b or upper side link 20a and 
lower side link with a pusher 25 are linked to the ends of the center link 
19 which protrude to the front and rear of the said chain supporting 
trolley 22. As shown in FIG. 2, the center link 19 and top and bottom side 
links 20a, 20b are linked with a connecting pin 21 with a T-letter head on 
both ends as described above, and when the upper side link 20a and lower 
side link 25 with a pusher are linked to the center link 19, a T-shaped 
fixing pin 25a which is protrudingly installed upward from one end of the 
lower side link 25 with a pusher, a T-shaped bolt 35a which is inserted 
upwardly through the hole on the other end of the lower side link 25 with 
a pusher, and a washer 35b and a nut 35c are used to affix the bolt 35a in 
place. 
As shown in FIGS. 2 and 5, in the assembled driving chain 18, the ends of 
the side links 20a, 20b located in the front and in the rear of the chain 
supporting trolley 22 and the ends of the upper side link 20a and the 
pusher equipped lower side link 25 adjoin the sides 29a, 29b in the 
longitudinal direction of the plate shape spacer 29 which protrude in the 
longitudinal direction from the vertical portions 27a, 28a of the trolley 
22. Consequently, when the driving chain 18 becomes loose and the side 
links 20a, 20b, 25 collide against both protruding sides 29a, 29b of the 
plastic plate shape spacer 29 and no metallic clanking noise is generated. 
If the driven chain 18 has a wide interval (chain link pitch) between 
connecting pins 21, as shown in FIG. 9, the length in the longitudinal 
direction of the vertical free spaces 19a and 19b in the link remaining in 
the front and rear of the said chain supporting trolley 22 becomes longer 
when the chain supporting trolley 22 is installed to the center link 19. 
This enables the smooth insertion of the T-shaped connecting pin 21 
through the vertical spaces 19a, 19b in the link 19 without the need to 
provide a notched concave portions 29c and 29d to front and rear sides 
29a, 29b of the plate shape spacer 29. 
Even with a short pitch driving chain 18 which enables the insertion of the 
T-shaped connecting pin 21 though the vertical spaces 19a and 19 of the 
center link 19 only when the notched concave portions 29c, 29d are 
provided to both front and rear sides 29a, 29b, of the plate shape spacer, 
it may not be the plate shape spacer, it may not be necessary to provide 
notched concave portions 29c, 29d to the plate shape spacer 29. This 
applies only if the chain supporting trolley 22 is attached to the center 
link 19 with side links 20a, 20b, 25 connected on both ends. 
As shown in FIG. 1, the pusher 24 propels a transport carriage 1 by pushing 
the driven dog 10, but the antirunaway piece 11 which is located in the 
longitudinal direction behind the pusher 24, prevents the transport 
carriage 1 from going forward at a speed higher than that of the pusher 24 
of the driving chain 18 by retaining the pusher 24 between the driven dog 
10 and the antirunaway piece 11. This can be especially important when, 
for example, when the route of travel is downhill. 
The antirunaway piece 11 is vertically rockably pivoted from the transport 
trolley 3 with a spindle 40 as shown in FIGS. 10 and 11, and is held in an 
upright position, as illustrated, by gravity due to the weight of an idle 
end 41 hanging down in the rear of the antirunaway piece 11. A plastic 
cushioning member 42, such as a nylon 6, is installed on a contact face of 
the antirunaway piece 11 which is contacted by the pusher 24 when the 
pusher 24 overtakes and passes the antirunaway piece 11. 
As shown in FIGS. 12 and 13 the cushioning member 42 is a long strip 
snapped into the back of the antirunaway piece 11. The T-shaped cushioning 
member 42 has a stem 45 with a longitudinal slot 44 forming two elastic 
ends on the end of the stem. Snap retaining shoulders 43 are formed in the 
elastic ends so that upon insertion of the stem 45 into a hole 47 in the 
antirunaway piece 11 anchored within the antirunaway piece. A cavity 46 is 
provided in the rear surface of the antirunaway piece 11, to permit the 
nesting of the cross piece of the T-shaped plastic cushioning member 
within the cavity with its top surface being substantially flush with the 
adjacent surfaces of the antirunaway piece. 
With the presence of the said cushioning member 42, when the pusher 24 
collides against the back of the antirunaway piece 11 and the pusher 
passes over it by tilting the antirunaway piece 11 forward, the pusher 24 
glides over and in contact with the cushioning member 42 without the 
occurrence of a metallic clanking noise. 
As shown in FIGS. 11 and 14 when the antirunaway piece 11 is not tilted 
forward, but is in its upright position, its idle and 41 contacts a 
surface 48 in a vertical rear wall 49 of the mounting of the rear wheel 12 
of the transport trolley 3. A cushioning member 50 with a protruding 
abutment cushioning surface 50a is retained within this surface 48 
somewhat similarly to the retention of the plastic cushioning member 42. 
The cushioning member 50 is a ring shape formed from plastic such as a 
fluoro rubber, and has a round head with a cushioning surface 50a. A 
circular shaped retaining shoulder 51 at the end of a stem 53 containing a 
slot 52 assures the retention of the cushioning member within a recessed 
surface portion 54 and through a hole 55 within the wall 49. 
With the presence of the said cushioning member 50, when the antirunaway 
piece 11 which is stricken by the pusher 24, then tilts forward as the 
pusher passes thereover, it will recover its original position under the 
effect of gravity. The idle and 41 will abut against the cushioning 
stopper surface 50a of the cushioning member 50. Due to the cushioning 
effect no metallic clanking noise will be generated, since no metal to 
metal contact takes place. If desired, the cushioning member 50 can be 
installed within the idle end 41 of the antirunaway piece 11 instead of in 
the wall 49, or in both the idle end 41 of the antirunaway piece 11 and 
the rear vertical wall 49 in the transport trolley 3. 
As shown, for example, in FIG. 2, the sides in the longitudinal direction 
of the pusher 24 which is downwardly protrudingly mounted from the driving 
chain 18, are slightly slanted so that the width of the pusher in the 
longitudinal direction increases toward its lower end. This is to prevent 
the generation of downward pressure on the driven dog 10 and the transport 
trolley 3. As shown in FIG. 15 a bottomed cylindrical plastic cushioning 
member 60 can be fitted over and attached to the pusher 24. 
The cushioning member 60 is formed from a thermoplastic material and is 
applied over the pusher 24 by expanding the opening of the heated and 
softened cushioning member 60 and fitted if over the pusher 24. The cooled 
and hardened cushioning member 60 will closely fit to the pusher 24. A 
cushioning member 60 with proper elasticity can also be applied over the 
pusher 24 without heating. One can also employ a heat shrinkable plastic 
material and closely fit such a cushioning member 60 over the pusher 24 by 
heating. Due to the outward slanting sidewalls of the pusher 24 the 
cushioning member 60 fitted over and fixed to the pusher will not 
unexpectedly come off even if no adhesive is used. 
The pusher 24 need not be located at the lengthwise center of the side link 
25 but can also be located at the end of the side to which the fixing pin 
25a for linkage is protrudably installed, as shown in broken lines in FIG. 
15. 
As further shown in FIG. 16, when an alternatively shaped straight pusher 
61 is used, which is a prism with parallel longitudinal sides, an adhesive 
is required to attach a straight walled cushioning member 62 to the 
straight pusher 61. 
The cushioning members 60, 62 are both effective to suppress noise 
generated both when the pushers 24 and 61 abut against and tilt the 
antirunaway piece 11 shown in FIG. 10, and when the pushers 24 and 61 
impact upon the driven dog 10. Because these cushioning members 60, 62 
cover both the bottom and rear of the pushers 24, 61, it is possible 
effectively to suppress both the screeching noise of the gliding contact 
generated when the bottom surface of the pushers 24, 61 slides in contact 
with the rear of the tilted forward antirunaway piece 11, and the sound of 
impact when the antirunaway piece 11 from behind abuts against the rear of 
the pushers 24, 61. Therefore, when the pusher is cushioned as shown in 
FIGS. 15 or 16, the cushioning member 42 of the antirunaway piece 11 can 
be eliminated, or both forms of cushioning can be employed together. 
It can also affix to the driven dog 10 an appropriate cushioning member, 
depending on the form of the driven dog.