Turnable cylinder for a conveyor system

A turntable for a conveyor system includes a cylinder having a longitudinal axis mounted to a stationary base plate; a non-rotatable piston disposed within the cylinder and mounted for reciprocal movement along the longitudinal axis; a bushing disposed about the longitudinal axis of the cylinder for rotatably mounting a plate for supporting an article and a stabilizing device coaxially mounted with the bushing for stabilizing the article supporting device during rotation. The article supporting device is raised and lowered with respect to the base plate by the reciprocal movement of the piston but its rotational movement is independent from that of the piston.

FIELD OF THE INVENTION 
The present invention relates in general to apparatus for changing the 
orientation or alignment of articles being transported by a conveyor 
system and, more particularly to elevating turntables. 
BACKGROUND OF THE INVENTION 
In order to transfer articles from one end of an assembly plant or 
warehouse, conveyor systems are known which include a plurality of 
intersecting conveying sections and turntables for changing the 
orientation of articles being conveyed, or the direction of travel 
thereof, or both. Turntables which are currently available include those 
designed for rotating articles on a roller conveyor system and/or rotating 
a conveying section of a conveyor system. With these known systems, the 
turntable is usually disposed in a gap between two sections of a 
non-contiguous conveyor. As a result, several drawbacks exist in that 
complicated turntable structures are needed for realigning or reorienting 
an article being conveyed. 
In particular, the article is handled more than necessary as it moves 
across at least three conveying sections. For example, articles or loads 
are received from one conveying section onto a platform of the turntable. 
The turntable is rotated through a predetermined angle and then the 
articles are discharged onto a second section of the conveyor system. The 
transfer or discharging operation may be done manually or automatically 
via driven rollers. Likewise, the turntable maybe rotated manually or by a 
power unit. To assist in the rotating operation, turntables can include 
means for lowering and raising the articles in relation to the conveying 
sections. Thus, are several mechanisms are required to rotate an object. 
This could present problems to an assembly process where stability of an 
object is extremely important and repositioning of the object being 
conveyed is necessary so that an operator can do precision work from one 
side of an assembly line. 
U.S. Pat. Nos. 2,897,948 to Cranston, Jr. and 3,100,039 to Oderman et al. 
disclose a turntable including elevating means and a platform where the 
piston providing the reciprocal movement of the elevating means is spaced 
from and parallel to the central axis of the platform supporting the load 
to be reoriented. Consequently, Cranston and Oderman employ an arrangement 
including an intermediate lever and a cam which indirectly actuates the 
raising or lowering operation of the turntable platform. A gear and chain 
arrangement or plurality of air cylinders provides the rotational 
movement. Not only are these turntables complicated in structure, the 
reciprocal and rotational movement thereof may jolt the loads which could 
be detrimental during the assembly of delicate parts (e.g., top heavy 
articles or electronic components), or the banding of separate items into 
a single unit. Further, the platforms of such conventional turntables 
include a plurality of openings spaced to overlie conveying rollers which 
complete the gap between conveying sections. When such a platform is 
lowered, the supported article/load rests on the conveying rollers so that 
articles can be pushed or conveyed between sections. However, these 
conventional platforms limit the angular orientation of articles to 
quarter turns. (i.e., 90.degree., 180.degree., 270.degree., 360.degree.). 
A powered turntable assembly having five spaced-apart air jack assemblies 
which raise and lower a turntable platform within a conveying section is 
taught by U.S. Pat. No. 4,519,493 to Dyer. This multiple jack assembly 
provides added stability in the extended position enabling an off-centered 
load to be raised and rotated. But, this turntable is designed for 
rotations in increments of 90.degree.. Moreover, a larger number of 
mechanical connections, as well as pneumatic assemblies, are necessary to 
complete this structure. Thus, the turntable is expensive to manufacture 
and to maintain in working condition. 
U.S Pat. No. 4,456,116 to Jarman discloses a round platform turntable 
disposed between two roller conveyor sections and two shortened roller 
sections. By activating a hydraulic cylinder, a piece of sheet metal 
positioned on the shortened rollers over the lowered platform turntable is 
raised above the conveying rollers. As a result, the raised sheet metal 
can be adjusted and aligned with any desired angle by rotating the 
platform via a shaft attached to the cylinder. Once the sheet metal is 
rotated the desired angle, the hydraulic cylinder is activated to lower 
the sheet metal onto the shortened rollers for continued conveying. 
However, this system is not concerned with heavy loads or ensuring 
stability of a conveyed article while being raised or in the extended 
position. 
According to Jarman, the shaft is rotatable about the longitudinal axis of 
the cylinder. Thus, forces due to a load supported on the turntable 
platform are transferred through the rotatable shaft and are distributed 
against the side walls of the shaft and/or hydraulic cylinder. 
Accordingly, the lifting as well as rotation of a heavy load produces 
friction, which wears the sealing components of the cylinder requiring 
replacement or repair. Moreover, the side and load thrusts applied by a 
load's weight during the rotational and reciprocating motions deteriorate 
the mechanical connection of the rotating shaft which is initially stable, 
along with the rubber seals or gaskets disposed on either end of the 
hydraulic cylinder. Consequently, wobbling is associated with the rotation 
of such rotatable elevating turntables requiring frequent repair and 
maintenance. 
Accordingly, there is a need in the conveyor art for a turntable of simple 
construction which provides increased stability of a load carried by a 
platform in an extended position and during rotation. Moreover, there is a 
need for a turntable that offers infinite flexibility in precision 
alignment and orientation of conveyed articles. 
OBJECTS AND SUMMARY OF THE INVENTION 
The principle object of the present invention is to provide a turntable 
apparatus for a conveyor or system which can lift and rotate a load being 
conveyed through any desired angle while maintaining a level 
load-supporting surface. 
It is a further object to provide an elevating turntable apparatus with 
increased load capacity, and a longer operating life thereby minimizing 
the maintenance costs associated therewith. 
It is another object of the present invention to provide an elevating 
turntable cylinder with increased load capacity which allows the platform 
supporting a load to freely rotate, without having to rotate the entire 
piston of the cylinder. 
It is further object of the present invention to provide an elevating 
turntable cylinder which increases the stability of a supported load when 
the cylinder is in the extended position and has an increased side load 
capacity over standard air cylinders. 
Yet another object of the present invention is to provide an elevating 
turntable cylinder of simple construction that is inexpensive to 
manufacture and to maintain. 
Another object of the invention is to provide a dual track conveyor system 
which offers the flexibility of changing the conveying direction of the 
load by shifting the load from one track section of the conveyor system to 
another. 
In summary, the above objects are achieved by the turntable cylinder of the 
present invention which includes a cylinder mounted to a stationary base 
plate, a non-rotatable piston disposed within the cylinder and mounted for 
reciprocal movement along a longitudinal axis of the cylinder, a bushing 
mechanism co-axially disposed about the cylinder axis for rotatably 
mounting a platform for supporting a load, and a stabilizing device for 
providing smooth rotation and precise re-orientation of a load where the 
platform is raised and lowered with respect to the base plate by the 
reciprocal movement of the piston. 
The turntable cylinder of the present invention is employed as a device for 
changing the direction of travel of articles being conveyed on a dual 
track conveyor system including a first track section for conveying 
articles in a first direction and a second track section intersecting at 
an angle with the first track section for conveying the articles in a 
second direction. 
A feature of the present invention is that the bushing mechanism is mounted 
within a recess formed in the piston providing lateral support and 
includes two sets of bearings which enable manual rotation of the 
platform. 
A further feature of the invention is that the bushing mechanism of the 
present invention freely rotates within the piston recess and the 
turntable cylinder includes elements to temporarily stop and secure the 
platform against rotation. 
Another feature is that the turntable cylinder according to the invention 
is a full stroke cylinder which provides increased stability of the load 
when the cylinder is in its extended position.

DESCRIPTION OF THE PREFERRED EMBODIMENT 
Referring to FIGS. 1 and 6, a conveyor system A may include two track 
sections 10, 12 representing two different paths of travel and a turntable 
cylinder B, B' disposed underneath a track section 10 (see FIG. 1) and at 
the intersection of track sections 10, 12 (see FIG. 6) in order to change 
the orientation of articles being transported thereon. Each track section 
includes two generally parallel, laterally spaced guide tracks 14, 16 
positioned along the opposite sides of the paths of travel, indicated by 
arrows X, Y. A load, such as a clothes dryer C, is placed on a carrier 
plate or pallet 18 which is moved along track sections 10, 12 by conveying 
chains or the like. The conveying chains are schematically shown by 
phantom lines in the figures. 
The conveyor in FIGS. 1 and 6 may be an INDUSTRALINE.RTM. two strand 
conveyor manufactured by Industrial Conveyor Corporation and described in 
U.S. Pat. No. 4,930,623, the subject matter of which is incorporated 
herein. Accordingly, the conveyor system is not described in particularity 
herein. 
In one embodiment, guide tracks 14, 16 are supported at a desired height on 
pillar members 20 positioned at successive intervals along the length of 
the respective sections. For additional strength and mechanical integrity, 
a number of cross-members 22 connecting pillar members 20 and braces 24 
extending transversely between tracks 14, 16 may be provided. The length 
of cross-members 22 and braces 24 may vary to obtain conveyors of varying 
widths to accommodate different articles. 
In order to positively and precisely reorient articles being conveyed along 
an assembly line, for example, a turntable cylinder B can be provided 
between guide rails 14 of dual track section 10. As illustrated in FIG. 1, 
the side of clothes dryer C facing assembly line workers can be easily 
changed from the front side to the rear side by rotating dryer C 
180.degree. via turntable cylinder B. While a clothes dryer is shown for 
simplicity in the drawing, the turntable cylinder B according to the 
invention can be used to smoothly reorient loads requiring rotations of 
any increment without interfering with delicate and precise electrical 
work for example. Heavier loads can be reoriented as well without tilting 
or damaging the component alignment of turntable cylinder B. 
Another embodiment of the turntable cylinder of the invention employs a 
modified platform as shown in FIG. 6 and is designated B'. Turntable 
cylinder B' is positioned at the intersection of track sections 10, 12. 
With this modification, a clothes dryer C traveling in the Y direction 
along track section 12 can shift to track section 10 in the X direction. 
TURNTABLE ELEVATING STRUCTURE 
As can be seen from FIGS. 1 and 2, turntable cylinder B can be mounted on a 
channel 26 so that it is centrally disposed between and below conveyor 
chains of a track section 10 when in its lowered position. Channel mount 
26 can be attached, via bolts 27 and spacer blocks 27', to the bottom of 
guide tracks 14 so that channel mount 26 spans track section 10 above 
cross-members 22. The length and width of channel mount 26 varies 
depending upon the width of track sections 10, 12 and the size of 
turntable cylinder B to be positioned there between. 
A stationary base plate 28 is attached to channel mount 26 via conventional 
fasteners, such as screws shown by hidden lines in FIG. 2. A cylinder 30 
having a longitudinal axis L is disposed on stationary base plate 28, 
preferably within a circumferential groove 31 formed in base plate 28. A 
non-rotatable piston 32 (see FIG. 4) is received in cylinder 30. 
Piston 32 is mounted for reciprocal movement along the longitudinal axis L 
of cylinder 30 with respect to stationary base plate 28. A pneumatic 
system is preferably used for the lowering and raising system as will be 
described below. However, a hydraulic system may be used. 
In an preferred embodiment, a piston rod 34 is inserted through a hole 28a 
formed through base plate 28 and into piston 32 for guiding the raising 
and lowering of piston 32. A screw threaded bore 36 is formed in the lower 
end 32a of piston 32 adjacent stationary base plate 28, and a first 
threaded end 34a of piston rod 34 is threadedly received within threaded 
bore 36. Circumferential groove 31 is preferably co-axially disposed about 
hole 28a in base plate 28 so that piston 32 and piston rod 34 are aligned 
with longitudinal axis L of cylinder 30. 
Base plate 28 is provided with inlet bores 28b and outlet bores 28c which 
communicate with the interior of cylinder 30. Appropriate fluid connection 
means 39 are inserted in inlets 28b and are connected via suitable hoses 
(not shown) to provide pressurized air of fluid to the interior of 
cylinder 30. 
A bushing 38, which may be ceramic, is disposed in hole 28a which may be 
drilled through the center of base plate 28. Bushing 38 includes a flange 
38a which extends over and rests against base plate 28 creating a seat for 
piston 32 in its lowered position, as shown in FIG. 4. Thus, an open space 
within the bottom of cylinder 30 is created for receiving a cushion of air 
or other appropriate fluid from outlet bores 28c. As a result of this 
structure, a level straight-line lifting motion is achieved as the 
pneumatic or hydraulic force is uniformly applied to the lower piston end 
32a of piston 32. Preferably, cylinder 30 and piston 32 form a full-stroke 
cylinder so that, even when piston 32 is raised within cylinder 30, a 
substantial portion of its sidewall can rest against the interior of 
cylinder 30 thereby providing increased stability over standard air 
cylinders. 
Two sealing rings 40 are positioned about piston rod 34 on either side of 
the bushing 38 to provide a shock absorbing cushion about bushing 38 and 
to seal opening 28a. In addition, lip seals 42 are disposed about the 
bottom ends of piston 32 and bushing 38. Other appropriate sealing means 
or arrangements for preventing air or fluids from escaping from the 
interior of cylinder 30 can be used which would be readily apparent to 
those having ordinary skill in the art. 
As shown in FIG. 2, a source of air or fluid (not shown) may be fed through 
air manifold 43 in guide track 14 as described in U.S. Pat. No. 4,930,623. 
Outlet valves 43a are provided along track 14 to tap the pressurized air 
or other fluid which flows through suitable connection hoses (not shown) 
to fluid connection means 39 of base plate 28. 
In order to limit the reciprocal movement of piston 32, a stop block 44 is 
screwed on the other threaded end 34b of guide rod 34. Between base plate 
28 and stop block 44, a spring 46 is disposed in tension in order to 
absorb vibration caused by sudden pressurization within cylinder 30. 
Spring 46 may also serve as a return spring if a single acting cylinder is 
employed. For added protection, a rod guard 48 is attached to the bottom 
of stationary base plate 28 surrounding guide rod 34, spring 46 and stop 
block 44. 
At the upper end 34b of piston 32, a rotation bushing 50 is rotatably 
mounted which is capable of supporting the weight of a load C during the 
reorientation operation. A top plate 52 (see FIG. 2) is fastened to 
rotational bushing 50 (shown in hidden lines) and serves as a platform for 
raising an object loaded on pallet 18. The shape of top plate 52 may be 
round or rectangular. Top plate 52 is preferably made of metal and may 
have recessed surfaces 53 for receiving fasteners such as screws or bolts 
54 flush therewith (see FIG. 5). 
According to the invention, top plate 52 supports pallet 18 raising and 
lowering the same with respect to base plate 28 by the reciprocal movement 
of piston 32 and rotating the same via its connection with rotation 
bushing 50. A preferred raised position is slightly above guide tracks 14, 
clearing the side frames thereof, so that the raised pallet 18' avoids 
interference with the side frames while being supported and rotated by top 
plate 52' as shown in phantom in FIG. 2. As a result, pallet 18, shown in 
solid lines, is raised over the conveying chain or gears of the conveyor 
system and cannot be moved in the conveying direction while in the raised 
extended position. Thus, the raised and reoriented load will remain 
stationary while being worked on. 
HUB ASSEMBLY STRUCTURE 
As can be seen from FIGS. 2 and 3, a hub assembly 56 is co-axially mounted 
about cylinder 30, and a locking device 58 including a rotatable cam 60 is 
attached to base plate 22 so that a bottom edge 56a of hub assembly 56 
rests against cam 60 in the raised position. Hub assembly 56 is attached 
to rotation bushing 50 so that it rotates therewith and includes a side 
wall 56b extending over the sides of cylinder 30. Locking device 58 may be 
mounted so as to be stationary on base plate 28. 
Hub assembly 56 may be connected to rotation bushing 50 by conventional 
fastening means, such as bolts 54. In addition, the connection of hub 
assembly 56 with top plate 52 can be achieved with fasteners or bolts 54 
which can be received within recesses formed on top plate 52. As a result, 
top plate 52 and hub assembly 56 are connected together and rotate 
together with rotation bushing 50 about the longitudinal axis L of 
cylinder 30. 
The bottom edge 56a and side wall 56b of hub assembly 56 are designed with 
elongated slots 62 (see FIG. 3) and/or notches 64 (See FIG. 2) for 
interaction with cam 60 of locking device 58. When piston 32 is in its 
lowered position, cam 60 is engaged with an upper portion of an elongated 
slot 62, thus securing hub assembly 56 and top plate 52 against rotation 
as shown in FIG. 2. 
The spacing between slots 62 formed in hub assembly 56 would depend upon 
the angle of intersection of track sections 10, 12 and/or the desired 
rotation of a load C on top plate 52. For example, two elongated slots 62 
would be disposed 180.degree. apart on side wall 56b of hub assembly 56, 
as shown in hidden lines in FIG. 2, in order to reverse the forward 
position of a load. If a rotation in 90.degree. increments is required, 
the pair of slots 62 would be spaced from each other at an 90.degree. 
angle and so on. However, for a rotation of 360.degree. only a single slot 
62 is required. 
Elongated slots 62 are preferably of an inverted U-shape with one leg 62a 
of the "U" being shorter than the other leg 62b and arranged so that the 
short legs 62a of elongated slots 62 face each other forming a shorter 
side wall portion 56b'. That is, the extension length of side wall portion 
56b' is shorter than the extension length of side wall 56b between the 
longer legs 62b of slots 62. 
Accordingly, when piston 32 (and thus, hub assembly 56) is in the raised 
position, cam 60 rests against a stop portion 62d of the longer leg 62b of 
slot 40. However, a portion of cam 60 is still between legs 62a, 62b of 
slot 62. As a result of this structure, hub assembly 56 can only be 
rotated in a single direction by applying a deliberate force to the load C 
supported by top plate 52. Once the initial deliberate force pushes the 
bottom edge 56a of hub assembly 56 over cam 60, the hub assembly will 
rotate until the next slot 62 is reached. 
This arrangement of locking device 58 and slots 62 does not allow rotation 
bushing 50 to continually rotate. More importantly, locking device 58, in 
conjunction with slots 62, does not allow rotation of top plate 52 and its 
load C in either direction once cam 62 is interlocked within the legs 
62a,b of slot 62. Thus, an assembly worker can even work on a light object 
without causing the platform to rotate. 
In the elevated or raised position, cam 60 follows the contours of edge 56a 
of hub assembly 56 until a stop portion 62d which extends past side wall 
portion 56b' stops the rotational movement of hub assembly 56. At this 
point the load has reached its desired position and piston 32 can be 
lowered, causing cam 60 to interlock with slot 62 securely holding top 
plate 52 and hub assembly 56 against rotation. 
In addition to elongated slots 62 which control the maximum amount of 
angular rotation allowed in one direction (i.e., clockwise or 
counterclockwise), temporary stop notches 64 can be formed at 
predetermined intervals on edge 56a of sidewall portion 56b'. These stop 
notches 64 may be placed at increments of 45.degree. or other angles 
depending upon the desired position of the articles being assembled and 
the operations to be performed thereon which determine when the angle at 
which the article should be stopped. As cam 60 follows bottom edge 56a, it 
in effect, holds rotation bushing 50 in a stable position. When a 
temporary stop notch 64 is reached, the rotation bearing 50 and hub 
assembly 56 drop a distance so that cam 60 firmly rests in notch 64. Thus, 
an operator would be able to shift load C to reorient the load and to work 
on it at this temporary stop. Moreover, several and any angular 
orientations (e.g., 15.degree., 35.degree., 70.degree., etc.) are possible 
by providing a temporary notch 64 at the desired angle. Accordingly, the 
article can be precisely positioned at any desired angle. 
ROTATION STRUCTURE 
In a preferred embodiment, piston 32 is formed with a centrally located 
recess 66. The depth and width of recess 66 is sufficient for receiving 
rotation bushing 50 that is capable of rotating load C a predetermined 
angle. 
Rotation bushing 50 is mounted within 2 sets of bearings 68, 70 which 
enable manual rotation of top plate 52. Rotation bushing 50 includes a 
lower part 50a of one diameter and an upper part 50b of a greater 
diameter. A first set of load-carrying bearings 70 is disposed in the 
bottom of recess 66 and surround lower body 50a when rotation bushing 50 
is disposed in recess 66. Spaced a distance from load-carrying bearings 70 
are side-loaded bearings 68 which surround upper body part 50b of rotation 
bushing 50. A snap ring or C-clip 72 secures side loading bearings 70 in 
place in a groove positioned on a side wall of recess 66. 
Between side-loaded bearings 70 and load-carrying bearings 68, another 
C-clip or bearing ring 74 is attached to grooves in upper part 50b 
securing rotation bushing 50 within recess 66. Bearing member 74 is 
disposed a slight distance d below bearings 68 to enable the desired 
reciprocal movement of rotation bushing 50 for the above-described locking 
and stopping features. Accordingly, rotation bushing 50 can free-float a 
distance d as shown in FIG. 4. Bearing plate 74 may be aluminum, for 
example, and is shaped so that its outer circumference can rest against 
the upper ends of load carrying bearings 68. 
In order to provide temporary locking positions at the bottom of slots 62 
and at notches 64, cam 60 and bearing member 74 are arranged so that in 
the extended position, rotation bearing 50 and hub assembly 56 can be 
raised a slight distance above cam 60 in order to start the rotation of 
top plate 52. Distance d is the distance hub assembly 56 drops so that cam 
60 firmly engages with temporary stop notch 64. 
Upper body part 50b preferably extends above the top surface 32b of piston 
32 when it is disposed within recess 66 and an attachment body 50c extends 
from the upper surface of upper body 50b. Attachment body 50c may include 
screw threads for securely attaching hub assembly 56 and/or top plate 52 
thereto. 
Attached to the other end of cylinder 30 is a top cap assembly 76 which 
additionally absorbs side load forces. Bolts 78 screw into top cap 
assembly 76 attaching the same to base plate 52 so that it rests against 
the upper end of cylinder 30 about the top end of piston 32 when it is in 
the lowered position as shown in FIG. 4. Top cap assembly 76 includes a 
metal ring 80, a bronze bearing ring 82 and a seal 84. Metal ring 80 
includes threaded bores for receiving the threaded ends of bolts 78. 
Bronze bearing 82 rests against the top of cylinder 30 and provides 
additional strength to the sides of cylinder 30 enabling increased side 
load capacity over standard air cylinders. Seal 84 is received in a 
circular cut out of metal ring 80 and prevents dirt and grime from 
entering the small gap between piston 32 and cylinder 30. 
OPERATION 
Referring to FIG. 1, turntable cylinders B can be disposed intermittently 
between pillar members 20 of a conveying section 10 of an assembly line. 
Loads, such as clothes dryers C, positioned on a pallets 18 are conveyed 
from a first assembly position to a second assembly position located above 
a turntable cylinder B. As described in U.S. Pat. No. 4,930,623, a drive 
unit (not shown) may be provided for automatically conveying loads C and 
stop assemblies (not shown) may be provided at suitable locations along 
section 10 to temporarily stop the movement of pallets 18 above a 
turntable cylinder B so that load C may be handled. Once pallet 18 is 
properly positioned above turntable cylinder B, the appropriate outlet 
valve 43a can be opened providing pressurized air or other fluid to 
connection means 39 of base plate 28. The fluid injected into the interior 
of cylinder 30 causes piston 32, along with top plate 52 and load C to 
rise in a smooth operation. During this process, elongated slot 62 moves 
up while stationary cam 60 follows its legs 62a, 62b holding top plate 52 
steady. The air or fluid supply is stopped so that top plate 52 is just 
above the conveying chains and/or gears of conveying section 10. Spring 46 
and stop block 44 ensure that the top block rises smoothly to that 
position. At this point, cam 60 rests between a portion of a short leg 62a 
and stop portion 62d (see FIG. 3). 
An assembly line worker then applies a deliberate force to either pallet 18 
or load C (depending on the durability and size of the load being 
conveyed), the assembly worker can smoothly and easily rotate pallet 18 
and load C supported thereon via rotation bushing 50 while cam 60 follows 
along edge 56a providing additional support which steadies the supported 
load C. This smooth and easy rotation continues into a temporary stop 
notch 64 is reached. 
At this point, load C is in another position for work to be done at the 
second assembly stage, for example as another face or apex of the load C 
is facing the assembly worker. After this work is completed, the assembly 
worker applies another deliberate force pushing notch 64 over stationary 
cam 60 enabling the rotation to continue in the initial direction until 
another stop notch 64 or an elongated slot 62 is reached. 
When a slot 62 is reached, pallet 18 can be lowered onto conveying chains 
of track section 10 to continue forward motion of load C to a third 
assembly stage. Pneumatic air injected within cylinder 30 is released from 
the cylinder during the lowering operation, thus allowing piston 32 to 
fall due to gravity and spring 46. Again, slot 62 is engaged with cam 60 
in the lower position securing hub assembly 56 and load C against 
rotation. 
With turntable cylinder B of the present invention, an assembly worker can 
control the rotation of the load C to be worked on, as well as easily move 
the load about its central axis. This enables several portions of the load 
C to be assembled at one assembly stage. Moreover, the turntable cylinder 
B according to the present invention is appropriate for both heavy and 
light loads as a full stroke cylinder can be used for heavier loads and 
the hub assembly 56 together with locking device 58 provides smooth and 
stable rotation of both heavy and light loads. 
ALTERNATIVE USES OF TURNTABLE CYLINDER 
In an alternative embodiment (see FIG. 5), the upper end 32b of piston 32 
may include a plurality of bores 90 co-axially disposed about recess 66 in 
the circumferential wall 92 of upper end 32b. As a result of this 
modification, piston 32 can be used with or without rotation bearing 50 
and its associated bearings 68, 70. For example, if no rotation of a load 
C is desired but the load is desired to be locked in place, turntable 
cylinder B can be easily modified to delete the rotation feature by 
removing rotation bearing 50 and its associated bearings 68, 70 and 
attaching top plate 52 on top of piston 32 via bolts 54 having threaded 
ends which are received in threaded ends of bores 90. 
Another possible use of the invention is as a turn-unit B' in a dual track 
conveyor system A as shown in FIG. 6. In this embodiment, the structure of 
turntable cylinder B is used with a conveying platform 96 attached to top 
plate 52 via screws (not shown). Alternatively, turntable platform 96 can 
be directly mounted to hub assembly 56 for rotation with rotation bearing 
50. 
A separate support stand 97 can be made from shortened pillars 20' and 
cross-members 22' to provide stable surfaces for mounting a heavy-duty 
channel 26 on which turn-unit B' is supported. The conveying platform 96 
includes 2 guide track sections 98 of a shortened length which form a 
conveying track on top plate 52. The length of turntable guide tracks 98 
and the size and shape of their associated platform 96 are designed so 
that a smooth interconnection with guide tracks 14, 16 of track sections 
10, 12 is achieved. 
In this operation, a pallet 18 moving in the Y direction is pushed onto the 
guide tracks 98 of turntable cylinder B'. This can be accomplished 
manually in conjunction with the driven chain of track section 12 by dog 
pawls attached to the driven chains or other conventional means. Once a 
load C is in the appropriate position on turntable guide tracks 98, an 
assembly worker can manually rotate turntable platform 96 and thus, pallet 
18, until turntable guide tracks 98 coincide with the guide tracks 14 of 
track section 10 which defines the X direction of travel. The load C and 
pallet 18 are then pushed onto guide rails 14 and its associated conveying 
means and the load C continues conveying in the X direction. As described 
in U.S. Pat. No. 4,930,623, a motorized chain and gear arrangement can be 
used to rotate top turntable platform 96. If such an automated rotation is 
desired, the appropriate stop assemblies and conveying means are provided 
as known to those skilled in the art. 
While this invention has been described as having a preferred design, it is 
understood that it is capable of further modifications, uses and/or 
adaptations of the invention following in general the principle of the 
invention and including such departures from the present disclosure as 
come within the known or customary practice in the art to which to 
invention pertains and as may be applied to the central features 
hereinbefore set forth, and fall within the scope of the invention and of 
the limits of the appended claims.