An accumulating conveyer is provided in which rollers are utilized which have a drive mechanism with a driven load-engaging portion in permanent frictional engagement with a driving portion. The drive mechanism includes an adjustable bias means so that the driving force between a driving portion and a driven portion is adjustable according to the characteristics of the loads to be conveyed. A friction pad is positioned between a disc in the driving portion and a disc in the driven portion of the drive mechanism; the two discs are urged against the friction pad by a compression spring. When the weight of a load in contact with the driven portion is below a predetermined value, the friction between the friction pad and the two discs is sufficient to cause the two discs and the friction pad to rotate conjointly thereby coupling the driving portion to the driven portion. When the weight of the load, or the weight of the load plus other resistance to movement of the load, exceeds the predetermined value, slippage occurs between the friction pad and the two discs thereby uncoupling the driving portion from the driven portion. Only selected ones of the rollers include drive mechanisms, the number and spacing of rollers with drive mechanisms, the number and spacing of rollers with drive mechanisms being determined by characteristics of the loads to be conveyed. The conveyer can be used to column accumulate, and, with the addition of brakes actuated by a switching mechanism, to zone accumulate.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
The present invention relates generally to a conveyer system and more 
particularly is directed to a new and improved accumulating conveyer 
capable of conveying loads having a wide range of predetermined weights, 
including heavy loads, and accumulating them either against each other 
(i.e., load-to-load or column accumulation) or in spaced relation to each 
other (i.e., zone accumulation). 
2. Description of the Prior Art 
Accumulating conveyers of various types are known in the prior art. Prior 
art conveyers suitable for carrying relatively heavy loads are generally 
of one of two types: roller flight conveyers and reciprocating gravity 
accumulating conveyers. Roller flight conveyers utilize rollers which are 
freewheeling and which only rotate by inertia when a load passes over 
them. The entire set of rollers, in a manner resembling an endless belt 
driven between two pulleys, is moved in a direction transverse to the axes 
of the rollers thereby carrying the loads along. Disadvantages of the 
roller flight type conveyers include the inability to vary the end 
pressure (i.e., the pressure which builds up as loads accumulate against 
each other) and the difficulty of using such conveyers to zone accumulate. 
Reciprocating gravity accumulating conveyers, the second type of conveyer 
presently used to convey heavy loads, operate by shuttling freewheeling 
rollers back and forth while the loads move by gravity. Conveyers of this 
type have the disadvantage of being incapable of zone accumulating. 
Further disadvantages of reciprocating gravity accumulating conveyers are 
that such conveyers require a change in elevation between the ends of the 
conveyer and that such conveyers can transport loads only in the downhill 
direction. 
Various types of conveyers in which the rollers are driven or rotated to 
cause the loads in contact with the rollers to be conveyed are also known 
in the prior art. Many of the drive mechanisms for rotating rollers in 
such prior art conveyers are either unsuitable for driving rollers when 
heavy loads are to be conveyed or are unsuitable for use in accumulating 
conveyer systems. The drive mechanisms for accumulating conveyers utilize 
various types of clutch mechanisms to permit the rollers to cease rotating 
when the load comes to a halt (e.g., at the end of the conveyer). It is 
also known to employ in a roller conveyer driven rollers wherein a rotary 
load-engaging roller portion is in permanent frictional engagement with a 
driving portion. In such prior art conveyers, however, the permanent 
frictional engagement between such portions causes overheating and 
considerable wear so that the magnitude of forces with which the driving 
portion transmits torque to the driven portion varies in response to 
several factors, including progressive wear on such portions. Overheating 
can cause excessive frictional engagement between driving and driven 
portions so that the driven portion continues to rotate when the load is 
at a standstill or so that the load travels with reference to the driven 
portion when it is desired to advance the load at a speed which is higher 
than the speed transmitted thereto by the driving portion when the driven 
portion rotates with the driving portion. One example of a conveyer in 
which rollers are driven by frictional engagement between a driving 
portion and a driven portion is described in U.S. Pat. No. 4,111,087 
issued to Pankratz et al. (see FIG. 4 and col. 5, lines 32-61 of the 
Pankratz et al. patent). 
The present invention utilizes a drive mechanism of the type in which a 
rotary load-engaging roller portion is in permanent frictional engagement 
with a driving portion. However, by use of a friction pad, the present 
invention overcomes the problems of overheating and excessive frictional 
engagement which exist with prior art devices. The present invention 
provides a drive mechanism particularly suitable for rotating rollers in 
an accumulating conveyer system for conveying a wide range of loads, 
including relatively heavy loads. 
SUMMARY OF THE INVENTION 
The present invention provides an accumulating conveyer in which selected 
rollers of the conveyer are driven by means of an improved drive 
mechanism. The drive mechanism permits a load-engaging roller tube to stop 
rotating without interrupting the application of driving power to the 
roller. The drive mechanism for the roller causes the driven portion of 
the roller (i.e., the portion including the roller tube) to slip with 
respect to a driving portion of the roller when a predetermined resistance 
to rotation is applied to the roller tube. Only selected ones of the 
rollers in the accumulating conveyer have a drive mechanism, the number 
and spacing of rollers with drive mechanisms being determined by 
characteristics of the loads to be conveyed so as to use a minimum number 
of rollers having such drive mechanisms. 
More specifically, the present invention provides an improved mechanism 
having a driving portion and a driven portion for each powered roller, but 
wherein the driven portion slips with respect to the driving portion of 
the roller when the resistance to rotation exceeds a predetermined force. 
The present invention utilizes a compression spring to hold a driving disc 
and a roller disc in contact with a friction pad which is sandwiched 
between them. The roller disc is rigidly attached to the roller tube so 
that the roller disc and roller tube rotate conjointly, and the driving 
disc is rigidly attached to a drive shaft so that the driving disc and 
drive shaft rotate conjointly. The drive shaft of each roller supplies 
torque to rotate the roller. When the driving disc and roller disc are 
held in contact with the friction pad with sufficient force by the 
compression spring, the two disc members rotate conjointly so that the 
rotation or torque of the drive shaft is transmitted to the roller tube. 
The amount of friction between the two disc members and the friction pad 
is determined by the force applied by the compression spring, the 
compression of which can be adjusted by threads on the end of the drive 
shaft. The compression spring is adjusted to provide sufficient friction 
between the friction pad and the driving disc and the roller disc to cause 
the roller tube to rotate under normal loads. When a load is halted over a 
roller by contacting a barrier or a load ahead of it (i.e., for 
load-to-load accumulation), or when a brake is applied to the roller 
(i.e., for zone accumulation), the amount of force resisting rotation of 
the roller tube is increased so that the friction supplied by the 
compression spring against the friction pad is not sufficient to cause the 
driving disc and the roller disc to rotate conjointly. As a result, at 
least one of the two disc members slips against the friction pad and the 
torque provided by the drive shaft is not sufficient to rotate the roller 
tube. 
Column (i.e. load-to-load) accumulation is provided by the present 
invention when the leading load on the conveyer engages a stop or barrier 
thereby causing the driving force between the driven portions and the 
driving portions of the powered rollers beneath that load to be overcome 
so that the driven portions stop rotating. Successive loads react in a 
similar manner as they come to rest against preceding loads. When the 
leading load is removed from the conveyer, the succeeding loads advance 
until the next successive load engages the stop. 
Zone accumulation is provided by the present invention when a leading load 
actuates a switch mechanism as it engages a barrier or stop. The switch 
mechanism causes a brake to be applied against the surface (i.e., against 
the roller tube) of the driven portion of a selected roller upstream from 
the load which actuated the switch mechanism. Application of the brake 
causes the driving force to be overcome and the driven portion to stop 
rotating so that the next load on the conveyer will stop when it reaches 
the preceding zone in which the roller tube has been stopped from 
rotating. This sequence is repeated for successive loads and successive 
zones. When the leading load is removed, the sequence is reversed, at 
which time the next successive leading load advances until it engages the 
stop and each of the succeeding loads advances into the next zone. 
Accordingly, it is an object of the present invention to provide an 
accumulating conveyer suitable for carrying a wide range of loads, 
including heavy loads, and which is capable of operating either with or 
without any change in elevation between the ends of the conveyer and which 
can transport loads in either direction. 
It is a further object of the present invention to provide an accumulating 
conveyer for which the end pressure which exists when loads are 
accumulated load-to-load can be controlled. 
It is another object of the present invention to provide an accumulating 
conveyer capable of zone accumulating wherein zones are effectuated by 
stopping the rotation of selected roller tubes by application of a brake 
against the surface of each of the selected roller tubes. 
This and other objects, advantages, and features shall hereinafter appear, 
and for purposes of illustration, but not for limitation, exemplary 
embodiments of the present invention are illustrated in the accompanying 
drawings.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
The present invention provides a drive mechanism 12 (see FIG. 1) which is 
positioned at the end of selected rollers 14 in an accumulating conveyer 
10. Non-driven rollers 13 (see FIG. 4) are also provided to support the 
loads being conveyed. The number and spacing of driven rollers 14 and 
non-driven rollers 13 is determined by the size, weight, and surface 
characteristics of the loads to be conveyed. Shorter or heavier loads or 
loads having uneven surfaces require relatively more driven rollers 14. 
Longer or lighter loads or loads having even surfaces permit relatively 
more non-driven rollers 13 to be used. The rollers 13 and 14 are mounted 
between frame members 16 and 18 of the conveyer 10. The roller tube 15 
surrounds the drive shaft 32 and drive mechanism 12, and is the portion of 
rollers 13 and 14 which engages the loads being conveyed. The conveyer 10 
is supported by suitable supports 20 and 22 as illustrated in FIG. 2. 
Depending upon the length of conveyer 10 and the weight of the loads to be 
conveyed, additional suitable supports can be utilized. Each roller 13 and 
14 is supported at its ends on a drive shaft 32 by antifriction support 
shaft bearings 24 and 26. Each drive shaft 32 is supported by antifriction 
support shaft bearings 28 and 30, which are mounted in frame members 16 
and 18, respectively. Sprocket 34 is splinably mounted on drive shaft 32 
of driven rollers 14 so as to rotate conjointly therewith while permitting 
sprocket 34 to slide axially on drive shaft 32. Power is applied via a 
roller chain 36 to cause the sprocket 34 and drive shaft 32 to rotate. The 
roller chain 36 is driven by suitable driving means 38 in a conventional 
manner as illustrated schematically in FIG. 2. It should be noted that 
non-driven rollers 13 can also be provided with sprockets 34. In that 
case, a limited torque which aids in conveying loads is provided to roller 
tubes 15 of non-driven rollers 13 due to the friction associated with 
bearings 24 and 26. 
Torque is transmitted from the drive shaft 32 to the roller tube 15 by the 
drive mechanism 12 as illustrated in FIG. 1. More specifically, drive 
mechanism 12 transmits the rotation of drive shaft 32 to roller tube 15 
when the resistance to rotation of roller tube 15 provided by the load 
does not exceed a predetermined value. To achieve this coupling of drive 
shaft 32 to roller tube 15, a spring 40 is compressed between spring 
compression plate 42 and driver disc 44. Spring compression plate 42 is 
held in a fixed, axial position on drive shaft 32 by roll pin 46 on the 
one side and spring 40 on the other side. The force provided by spring 40 
against spring compression plate 42 maintains spring compression plate 42 
in a position abutting against roll pin 46. The other end of spring 40 
abuts against driving disc 44. Driving disc 44 is splinably but slidably 
mounted to drive shaft 32 so as to rotate conjointly therewith while being 
slidable in an axial direction. Friction pad 48 is sandwiched between 
driving disc 44 and roller disc 50. Roller disc 50 is rigidly mounted, or 
mechanically coupled, to roller tube 15 so as to rotate conjointly 
therewith. When sufficient force is supplied by spring 40, driving disc 44 
is held tightly against one side of friction pad 48 and the other side of 
friction pad 48 is held tightly against roller disc 50. As a result, the 
friction between the one surface of friction pad 48 and driving disc 44 
and between the other surface of friction pad 48 and roller disc 50 is 
sufficient to cause driving disc 44, friction pad 48, and roller disc 50 
to rotate conjointly. Thus, rotation of drive shaft 32 is transmitted to 
roller tube 15 so that they rotate together. However, when the resistance 
to rotation of roller tube 15 is provided by the load contacting roller 
tube 15 is sufficiently great, the friction between the one surface of 
friction pad 48 and driving disc 44 and the friction between the other 
surface of friction pad 48 and roller disc 50 is not sufficient to prevent 
driving disc 44 and roller disc 50 from slipping relative to friction pad 
48 (i.e., the driving force supplied via drive shaft 32 is overcome). This 
slippage uncouples roller tube 15 from drive shaft 32 so that roller tube 
15 ceases to rotate. Friction pad 48 can be made of material similar to 
the type of material used for brake pads in various applications 
including, for example, automobile wheel brakes. 
The weight of the loads which can be carried on roller tube 15 without 
causing driving disc 44 and roller disc 50 to slip against friction pad 48 
is determined by the force applied by spring 40. The greater the force 
applied by spring 40, the greater the load that can be carried by roller 
tube 15 without slippage. The force applied to driving disc 44 by spring 
40 can be varied by adjusting the distance between spring compression 
plate 42 and driving disc 44 (i.e., by adjusting the degree to which 
spring 40 is compressed). This distance can be adjusted in the present 
invention by sliding drive shaft 32 towards or away from roller disc 50 
thereby sliding spring compression plate 42 relative to driving disc 44. 
This is accomplished by slidably mounting sprocket 34 on drive shaft 32 
such that drive shaft 32 can move axially with respect to sprocket 34 
while sprocket 34 remains in a permanent axial position aligned with chain 
36. Drive shaft 32 can be a hexagonal shaft, for example, with sprocket 
34, spring compression plate 42, and driving disc 44 having hexagonal 
holes through which the drive shaft 32 is mounted. 
In one embodiment of the present invention (see FIG. 1) the end of drive 
shaft 32 opposite sprocket 34 has threads 52 on which is threaded a nut 
54. Rotating nut 54 thereby causes drive shaft 32 to move in an axial 
direction with respect to bearing 30 and frame member 18. Thus, adjusting 
nut 54 adjusts the compression of spring 40, and, hence, the weight of the 
load which can be carried by roller tube 15 without slippage occurring. 
Shield 56, when in place, prevents unauthorized tampering with the 
adjustment of nut 54. 
A second embodiment of this feature of the present invention is illustrated 
in FIG. 5. In this embodiment, the end of drive shaft 32 has a hole 53 
that is internally threaded to receive a cap screw 55. The cap screw 55 is 
supported by pipe 57 and washer 57a and is threaded into hole 53. The head 
55a of cap screw 55 can have a socket (not shown) or a slot (not shown) to 
permit cap screw 55 to be adjusted with an Allen wrench or a screwdriver, 
respectively. Shield 56 can have a hole 56a (see FIG. 1) for permitting an 
Allen wrench or screwdriver to be inserted into the socket or slot in head 
55a of cap screw 55. 
In one embodiment of the present invention, load-to-load or column 
accumulation is provided. For load-to-load accumulation, each load 66 (see 
FIG. 2) is moved along conveyer 10 by the rotation of roller tubes 15 
until a barrier or restraint 68 is reached (i.e., in FIG. 2 the loads are 
moved from left to right). When a leading load 66' is restrained from 
moving by barrier 68, the force tending to prevent rotation of roller tube 
15 of driven roller 14 is increased sufficiently to overcome the driving 
force between the driven roller tube 15 and the associated drive shaft 32. 
Thus, roller tube 15 of the driven roller 14 beneath load 66' ceases 
rotating as load 66' comes to barrier 68. Roller tube 15 will cease 
rotating due to slippage of driving disc 44 and roller disc 50 against 
friction pad 48 when the load is restrained due to the increased 
resistance to rotation of the roller tube 15 beneath the restrained load. 
This prevents the roller tube 15 from continuing to rotate and thereby 
wearing against a load that has been halted. Roller tubes 15 of driven 
rollers 14 beneath succeeding loads 66 react in the same way when the 
succeeding loads come to rest against a preceding load. When the leading 
load 66' is removed from conveyer 10, successive loads 66 advance until 
barrier 68 is engaged by the next successive leading load 66", at which 
time the succeeding loads accumulate behind it in the manner described. 
In a second embodiment of the present invention, zone accumulation of loads 
is provided. With zone accumulation a spaced relation is maintained 
between loads as the loads accumulate, i.e., come to rest on the conveyer. 
FIGS. 2, 3, and 4 illustrate an actuating roller 58 pivotably mounted 
between frame member 16 and frame member 18. When a load 66 (see FIG. 2) 
passes actuating roller 58, actuating roller 58 pivots downward (see FIGS. 
3 and 4) thereby actuating an air limit switch or valve (not shown). After 
the load has moved beyond actuating roller 58, a counter bias (not shown) 
causes actuating roller 58 to pivot back to its normal position projecting 
above roller tubes 15 with the associated air limit switch or valve (not 
shown) not actuated. Actuation of the air limit switch or valve (not 
shown) causes a conventional pneumatic system (not shown) to apply a brake 
pad 64 directly against the surface of roller tube 15 upstream of the load 
66 which engaged an associated actuating roller 58. A brake pad 64 is 
urged against an associated roller tube 15 when an air bag 62 is inflated 
by the pneumatic system (not shown) in a convential manner. It should be 
understood that the function of the limit air switch or valve (not shown) 
could be accomplished in a variety of ways including, for example, by a 
photocell and light beam arrangement. Also, brake pad 64 could be urged 
against roller tube 15 by conventional mechanical means other than a 
pneumatic system. 
Application of brake pad 64 to a roller tube 15 stops the rotation of 
roller tube 15. Thus, the driving force between the driven roller tube 15 
and the drive shaft 32 is overcome. When a brake 64 is applied to a roller 
tube 15 by inflation of air bag 62, the drive shaft 32 of the roller 14 is 
uncoupled from the roller tube 15 by slippage of driving disc 44 and 
roller disc 50 on friction pad 48. Hence, a load will come to rest when it 
is positioned over a roller tube 15 to which a corresponding brake pad 64 
has been applied. 
Zone accumulation is accomplished using the foregoing arrangement as 
illustrated in FIG. 2. When load 66' is restrained by barrier 68, 
actuating roller 58' is engaged by load 66' and is pivoted thereby 
actuating an associated air limit switch or valve (not shown), which 
causes air bag 62' to be inflated by the pneumatic system (not shown). 
Inflation of air bag 62' urges brake pad 64' against a roller tube 15' in 
the preceding zone. Thus, roller tube 15' stops rotating, which in turn 
prevents load 66" from being conveyed forward. Similarly, load 66" is 
positioned over actuating roller 58" such that actuating roller 58" is 
pivoted thereby actuating an associated air limit switch or valve (not 
shown). Actuation of the air limit switch or valve causes air bag 62" to 
be inflated which urges brake pad 64" against roller tube 15" in the 
preceding (i.e., upstream) zone. Consequently, roller tube 15" stops 
rotating, which in turn prevents load 66'" from being conveyed forward. 
The process of pivoting actuating rollers 58 to actuate air limit switches 
and apply brake pads 64 repeats to stop successive loads in successive 
zones on conveyer 10. When the leading load 66' is removed, actuating 
roller 58' is released thereby causing brake pad 64' to release roller 
tube 15'. Hence load 66" advances to barrier 68. In a similar manner 
successive roller tubes 15 are released and successive loads are advanced 
to the next succeeding zone. 
Since actuating rollers 58 are pivoted so as to actuate an air limit switch 
each time a load passes over them, brake pads 64 are urged against 
corresponding roller tubes 15 thereby halting them as loads proceed along 
the accumulating conveyer. Consequently, each load positioned over a 
roller tube 15 that is halted is delayed until the load ahead of (i.e. 
downstream from) it is conveyed beyond the corresponding actuating roller 
58. As a result loads maintain a spaced relationship as they proceed along 
the accumulating conveyer. 
While the preferred embodiment of the invention has been illustrated and 
described, it is to be understood that the invention is not limited to the 
precise construction herein disclosed, and the right is reserved to all 
changes and modifications coming within the scope of the invention as 
defined in the appended claims.