Track and trolley with dual drive wheels having annular track engaging surfaces of different diameters

A track and trolley system that allows wall panels to be moved with a minimum amount of friction is disclosed. The system includes a track having a first rail, a second rail which is higher than the first rail, and a trolley having two drive wheels that engage the rails via annular track engaging surfaces of different diameters. Each drive wheel is independently rotatable in opposite directions. The system further includes a wall panel mount assembly haivng a housing integral with a movable wall panel and slide pads at track intersections to reduce the vertical elevational drop of a trolley when it moves across a track intersection.

FIELD OF THE INVENTION 
This invention relates to track suspension systems for supporting movable 
wall panels, such as those used to partition large rooms into smaller 
rooms. 
BACKGROUND 
Four objectives of trolley and track systems that suspend movable wall 
panels are: (1) to allow the walls to be moved with as little friction as 
possible; (2) to keep the wall panels properly centered within the track; 
(3) to reduce the shock caused by a trolley impacting a stationary object 
such as a track intersection and to allow panels to sway; and (4) to allow 
the panels to be moved across angular (as opposed to curved) track 
intersections without the trolleys dropping into gaps which usually exist 
in such intersections. No known system accomplishes all of these 
objectives. 
Single puck or disc trolleys such as disclosed in U.S. Pat. No. 4,084,289 
generally fail to reduce friction to an acceptable level because one side 
of the trolley rotates in a direction opposite to the direction the wall 
is moved. This problem was solved in U.S. Pat. No. 4,141,106 by using a 
canted puck, but such a system allows a panel to sway to an unacceptable 
level, and does not keep the wall panel properly centered in its track. 
Another method is to use a track having a pair of flanges, which engage two 
vertically spaced trolleys or pucks. In U.S. Pat. No. 4,159,556, the 
objective of such a system was to allow the trolley to easily traverse 
track intersections. However, such systems require twice as much contact 
between the trolley and track, increasing friction. Other systems, such as 
those described in U.S. Pat. Nos. 3,042,960, 3,879,799 and 4,401,033, 
provide for upper and lower discs, with only opposite sides of the upper 
and lower discs engaging the track. However, such systems are not only 
expensive to manufacture, but do not allow a standard wheeled trolley to 
be used in the track if desired. Other known systems do not adequately 
protect the joint of a trolley and wall panel, causing such joints to 
quickly wear from the shock resulting when a trolley is moved in a track 
intersection or when a panel sways. In addition, wall panels become stuck 
in track intersections in other known systems because the trolleys are 
prone to drop into the gaps in such intersections. 
SUMMARY OF THE INVENTION 
The invention comprises a track and trolley system that allows wall panels 
to be moved with a minimum amount of friction. The system includes a track 
having a first rail which may be horizontal, a longitudinally parallel 
second rail which is higher than the first rail, and a trolley having two 
drive wheels that engage the rails via annular track engaging surfaces of 
different diameters. Alternatively, the slanted rail of the track may 
include a short horizontal surface, to allow the track to be used with 
standard wheeled trolleys in addition to horizontal drive trolleys. 
The trolley utilizes a vertical shaft having an outer drive wheel having an 
annular track engaging surface which is rotatably mounted on the shaft. An 
inner drive wheel, also rotatably mounted on the shaft, has an annular 
track engaging surface with a smaller diameter than the diameter of the 
outer drive wheel's annular track engaging surface. The inner drive wheel 
may have either a horizontal lower surface or a substantially tapered 
lower surface, whereby its annular surface closest to the shaft is below 
its annular surface furthest from the shaft. If the lower surface of the 
inner drive wheel is tapered, it may be either concial or spherical. The 
inner drive wheel's annular track engaging surface is below the annular 
track engaging surface of the outer drive wheel. Each drive wheel may be 
independently rotatable in opposite directions. This eliminates the 
additional friction created by some prior art trolleys using a single 
rotatable bearing which engages both rails simultaneously. 
A major advantage of the invention is that its inner and outer drive wheels 
contact their respective tracks via annular surfaces of different 
diameters. This is important because it allows a more compact construction 
and because it reduces the vertical elevational drop when a trolley is 
moved through a track intersection. As long as the radius of the outer 
drive wheel track engaging surface is greater than the diameter of the 
inner drive wheel track engaging surface, the outer drive wheel will 
engage a track across an intersection gap before the inner drive wheel 
begins to drop into the gap. This is a significant improvement over the 
prior art, in which the engaging surfaces of counter-rotating drive wheels 
typically have equal radii. 
The system further includes a wall panel mount assembly having a housing 
integral with a movable wall panel. The housing has upper and lower walls, 
and an upper aperture capable of receiving a shaft to which a trolley is 
mounted. The housing encloses a nut into which the shaft may be screwed. 
The nut is surrounded by a resilient flexible block with washers located 
above and below the block. A second resilient flexible block of material 
is below the lower washer, and includes a cavity capable of receiving the 
shaft. 
The system also includes slide pads at track intersections to reduce the 
vertical elevational drop of a trolley when it moves across an 
intersection. An intersection may be an X, T, L or Y intersection. When a 
trolley is positioned in a track, there are vertical spaces between each 
drive wheel and the track. The slide pads occupy these spaces in a track 
intersection to keep the trolley at substantially same elevation and to 
prevent the trolley from dropping. The slide pads may be mounted to 
support just the outer drive wheel, or both inner and outer drive wheels. 
Also in the preferred embodiment, the outer drive wheel has a 
substantially horizontal lower surface to increase the contact area 
between the wheel and the slide pads in an intersection to provide 
additional support of the trolley.

DESCRIPTION OF THE PREFERRED EMBODIMENT 
FIG. 1 is a vertical section of a movable wall panel system with which the 
invention may be used. Movable panels 1 are suspended from trolleys 2 by 
pendant bolts 3. The trolleys 2 travel in track 4. One problem with prior 
systems is that when trolleys 2 are moved against stationary objects such 
as track intersections, trolleys 2 are subject to shock, thus causing them 
to wear. The present invention solves this problem as described below by 
connecting trolleys 2 to panels 1 using flexible mountings. 
FIG. 2 is a vertical section of the track and trolley system of the 
invention taken in the line of 2-2 of FIG. 1. The bottom surfaces of first 
rail 43 and second rail 44 are substantially coplanar so that track 4 may 
be held by C channel 5, which is attached to overhead structure by 
supporting bolts 6 and nuts 7. Height alignment bolt 8 abuts the top of 
track channel 5 so height of track channel 5 may be controlled. Guide 
walls 9 extend from track 4 to provide proper alignment of the trolley 2. 
Flanges 10 outwardly extend from guide walls 9 to serve as a soffit and to 
receive wallboards 11 which act as sound baffles. 
The trolley includes bolt 12, which serves as a shaft to support outer 
drive wheel bearing 21, bottom spacer 14, upper spacer tube 15, washer 16, 
lower spacer tube 17, sleeve bearings 18, lock washer 19 and jam nut 20. 
Sleeve bearings 18 should be freely rotatable, so their combined length 
should be greater than that of lower spacer tube 17. Outer drive wheel 
bearing 21 supports outer drive wheel 13, while bottom spacer 14 supports 
inner drive wheel bearing 22 which in turn supports inner drive wheel 23. 
Thus, outer drive wheel 13 and inner drive wheel 23 may independently 
rotate in opposite directions. 
The lower portion of bolt 12 is attached to movable wall panel 1. Movable 
wall panel 1 includes seals 24, which act as a sound seal and which help 
protect the trolley assembly from exposure to dirt and the like. 
It may be appreciated that the present invention allows a wall panel to 
hang plumb, keeping the trolley engaged on both sides of the track. 
FIG. 3 is a vertical section of the flexible wall panel mount assembly of 
the invention, showing how the mount allows swaying of a panel. Bolt 12 
extends from trolley assembly 25 and is secured to upper wall mount 
housing 26 by square nut 27. Upper wall panel frame 28 includes aperture 
29 through which bolt 12 extends. Bolt 12 has mounted thereon spacer tube 
30, which is secured by washer 31 and lock nut 32. Distal adjustment of 
the wall panel with respect to trolley assembly 25 is made by adjusting 
the extent to which bolt 12 is screwed into square nut 27. The distance 
between the trolley assembly 25 and movable wall panel 1 should be the 
same for all such assemblies and panels. Once the desired distance is 
obtained, lock nut 32 is tightened against washer 31 and spacer tube 30 to 
prevent bolt 12 from rotating with respect to square nut 27. Aperture 29 
has a diameter greater than spacer tube 30, so spacer tube 30 can move 
without hitting the edges of aperture 29. Spacer tube 30 abuts top washer 
33, which is positioned below upper wall mount housing 26 and above washer 
34. In between washer 34 and center washer 35 is nut retainer 36. Nut 
retainer 36 is a rectangular block of resilient flexible material such as 
rubber with a square hole in the center which holds square nut 27 and acts 
as a shock absorber. Beneath center washer 35 is trolley mount retainer 
37, which is a square block of resilient flexible material such as rubber 
with a hole through the center for receiving bolt 12. Trolley mount 
retainer 37 acts as a compression spring and shock absorber, and is held 
in place by lower wall mount housing 38. As shown more fully in FIG. 4, 
lower wall mount housing 38 is fastened to upper wall mount housing 26 by 
means such as welding, and supports trolley mount retainer 37. 
The shock absorbing characteristics of the flexible wall panel mount 
assembly are demonstrated in FIG. 3. when a movable wall panel is swayed 
out of a plumb position, top washer 33 pivots on its leading edge, causing 
a gap 39 between top washer 33 and upper wall mount housing 26. Nut 
retainer 36 partially absorbs the shock, and together with square nut 27, 
apply force on center washer 35, which in turn, together with bolt 12, 
compress trolley mount retainer 37 and absorb the remainder of the shock. 
Trolley mount retainer 37 acts like a compression spring and a shock 
absorber, and becomes increasingly stiff as deformation is increased. 
After displacement, nut retainer 36 and trolley mount retainer 37 return 
to their normal position. The stiffness of the mount may be changed by 
varying the durometer hardness of nut retainer 36 and trolley mount 
retainer 37. 
FIG. 4 is a vertical section of the flexible wall panel mount assembly of 
the invention taken from an angle perpendicular to that of FIG. 3, showing 
how the mount absorbs shock resulting from moving the trolley against a 
stationary object such as a track intersection. From the view of FIG. 4, 
it may be appreciated that lower wall mount housing 38 may be spot welded 
to upper wall mount housing 26 at weld points 40 and 41. Upon impact, top 
washer 33 pivots, causing a gap 42 between top washer 33 and upper wall 
mount housing 26. Nut retainer 36 partially absorbs the shock, and 
together with square nut 27, apply force on center washer 35, which in 
turn, together with bolt 12, compress trolley mount retainer 37 to absorb 
the remainder of the shock. 
FIG. 5 is a perspective section of the flexible wall panel mount assembly. 
From this view, it may be seen that upper wall mount housing 26 and lower 
wall mount housing 38 have mounted therein top washer 33, washer 34, nut 
retainer 36, square nut 27, center washer 35, and trolley mount retainer 
37. Bolt 12, which extends from the trolley, may be screwed into square 
nut 27, effecting the distance between the wall panel and trolley 
assembly. 
FIG. 6 is a perspective section of the trolley and track, showing the 
points at which the inner and outer drive wheels of the trolley engage the 
track. Although left rail 43 and right rail 44 may appear coplanar at 
first glance, closer examination reveals that right rail 44 is actually 
comprised of three separate longitudinal planar surfaces, 45, 46, and 47. 
As the lower surface of inner drive wheel 23 extends below the planar 
surface of outer drive wheel 13, inner drive wheel 23 engages left rail 43 
along its annular edge 48 with guide wall 9. However, planar surface 45 of 
right rail 44 is below the planar surface of left rail 43, so that the 
lower surface of outer drive wheel 13 does not engage either of these 
surfaces or longitudinal planar surface 46. Instead, the outer annular 
edge 49 of outer drive wheel 13 engages right rail 44 along longitudinal 
planar surface 47, which is adjacent to surface 46 and which upwardly 
extends from the plane defined by the surface of left rail 43. Right rail 
44 need not necessarily extend towards the trolley as shown in FIG. 6, so 
right rail 44 need not include planar surface 45 or 46. It is sufficient 
to practice the present invention if right rail includes only a planar 
surface for engagement of outer drive wheel 13 which does not engage inner 
drive wheel 23. The engaging surface of inner drive wheel 23 has a radius 
as opposed to a conical surface. This reduces the wheel's contact area 
with the rail, and the resulting friction when the trolley is moved in the 
track. 
FIG. 7 is a section of the trolley of the invention. Pendant bolt 12 serves 
as a mounting shaft for outer drive wheel bearing 21, bottom spacer 14, 
and upper spacer tube 15. Outer drive wheel 13 is fitted to outer drive 
wheel bearing 21 to be rotatable with respect to bolt 12. The construction 
of outer drive wheel 13 creates a cavity in which bottom spacer 14 is 
fitted to inner drive wheel bearing 22, which supports inner drive wheel 
23, allowing said wheel to rotate independently of both bolt 12 and outer 
drive wheel 13. Outer drive wheel bearing 21, bottom spacer 14, and upper 
spacer tube 15 are upwardly fitted against the top of bolt 12 by washer 
16, which in turn is supported by lower spacer tube 17, which is secured 
by lock washer 19 and jam nut 20. Sleeve bearings 18 are placed around 
lower spacer tube 17, and are freely rotatable thereon. The plane defined 
by the lower surface of said outer drive wheel 13 is immediately adjacent 
to the outermost surface of said inner drive wheel 23. 
FIG. 8 is an exploded partial section of the trolley of the invention, 
whereby the construction thereof as described above may be more fully 
appreciated. 
FIG. 9 is a perspective view of the track of the invention. Track 4 may be 
integrally formed from commercial quality hot rolled steel or extruded 
aluminum, and shaped using techniques well-known in the art and which do 
not form a part of the present invention. Track 4 includes left rail 43, 
right rail 44, left wall 49, right wall 99, left guide wall 50 and right 
guide wall 51. Left rail 43 has a horizontal planar surface. In the 
preferred embodiment as shown in FIG. 9, right rail 44 includes three 
separate longitudinal planar surfaces, 45, 46, and 47. Planar surface 46 
is coplanar with the left rail surface 43. Planar surface 45 angularly 
extends below planar surface 46, while adjacent planar surface 47 
angularly extends upwardly from planar surface 46. However, it is also 
possible to construct right rail 44 so it has no surface coplanar with 
left rail 43, and the entire right rail 44 merely angles downwardly from 
right wall 99. Right rail 44 may either terminate after the trolley 
engaging surface, or continue to right guide wall 51. Although such a 
construction would allow the trolley to engage the track as shown in FIGS. 
2 and 6, such a construction would not be capable of accommodating a 
wheeled trolley as shown below in FIG. 11, because right rail 44 would not 
contain a surface coplanar with left rail 43. Alternatively, planar 
surfaces 45 and 47 could be constructed to form adjacent "steps" to planar 
surface 46, the only requirement being that planar surface 45 be below 
planar surface 46, and planar surface 46 be below planar surface 47. 
FIG. 10 is a vertical section of the trolley of the invention, showing an 
alternate bearing and outer drive wheel configuration. Specifically, to 
support heavier wall panels, outer drive wheel 52 is supported by a larger 
outer drive wheel bearing 53, which in turn is secured to bolt 12 by both 
upper spacer 54 and lower spacer 55. Lower spacer 55 also supports inner 
drive wheel bearing 56. It may also be appreciated from FIG. 10 that the 
contact point 57 between inner drive wheel 23 and left rail 43 is 180 
degrees apart from contact point 58 of outer drive wheel 52 and right rail 
44, thus keeping the trolley level within the track. In addition, it is 
apparent that as the trolley travels through the track, inner drive wheel 
23 will rotate in a direction counter to that of outer drive wheel 52. 
It may further be appreciated that because outer drive wheel 52 does not 
contact right rail 44 between contact point 58 and right guide wall 51, 
this portion of right rail 44 need not necessarily be triplanar as 
described above. All that is necessary to practice the invention is that 
right rail 44 have some longitudinal surface that is above the surface of 
left rail 43, so that the respective surfaces may be independently engaged 
by the inner and outer drive wheels. However, such a construction would 
not prove suitable for a wheeled dolley as shown in FIG. 11. 
In FIG. 11, the track as described above is shown using a wheeled dolley of 
the type well known in the art. Thus, the advantage of the present 
invention may be appreciated because the track may be used not only with a 
trolley having inner and outer drive wheels as described above, but also 
with such wheeled dolleys. Specifically, bolt 59 is secured to shaft 
support 60. Support 60 supports shaft 61, on which wheels 62 and 63 are 
mounted. Wheel 62 engages left rail 43, while right wheel 63 engages the 
horizontal longitudinal planar portion 46 of right rail 44, which is 
coplanar with left rail 43. 
FIG. 12 is a vertical section of a track intersection of the invention, 
showing the slide pads 64 and 67 which reduce the vertical elevational 
drop in such intersections. The slide pads reduce vertical elevational 
drop of the trolleys in intersections by supporting the lower surfaces of 
the inner and outer drive wheels across an intersection before the center 
of the trolley crosses the intersection. Thus, when a trolley is in the 
middle of an intersection, it is fully supported by the slide pads, 
instead of dropping and being supported by the rails themselves. Left rail 
slide pad 64 has a flat lower surface 65, to accommodate the horizontal 
surface of left rail 43. The upper outer surface 66 of the pad is also 
horizontal, and supports outer drive wheel 13. The upper inner surface 71 
is tapered, and adapted to support inner drive wheel 23. 
Right rail slide pad 67 has inner and outer portions. The lower outer 
surface 68 is horizontal, and is capable of fitting against the horizontal 
portion 46 of right rail 44. The lower inner portion 69 is tapered at the 
same angle as the planar surface 45 of right rail 44. The upper outer 
surface 70 of the pad is horizontal and engages outer drive wheel 13. The 
inner upper surface 71 of the pad is angled at the same angle as inner 
drive wheel 23 to engage the same. Thus, when a trolley is moved into a 
track intersection, the slide pads occupy the vertical gaps between each 
drive wheel and the track, providing additional support for the trolley. 
Although the slide pads have been described with respect to the particular 
upper track surfaces and lower drive wheel surfaces described above, the 
invention only requires that the slide pads occupy sufficient space 
between such surfaces to support the drive wheels in a track intersection. 
It may thus be appreciated that both sides of the inner and outer drive 
wheels are engaged by the slide pad when the trolley is moved into a track 
intersection. This has the shortcoming noted above of the the opposite 
sides of each drive wheel rotating in a direction counter to the direction 
the panel is being moved, thus creating additional friction. Therefore, it 
is preferable for the slide pads to be made of a hard, low-friction 
material such as powdered metal, nylon or molydisulfide oil-impregnated 
nylon. 
FIG. 13 is a cut-away perspective view of the slide pads of the invention 
mounted in a track X intersection. It may be appreciated that in such 
track intersections, multiplanar rails 72, 73, 74 and 76 (referred to as 
the right rail above) are joined only with other multi-planar rails, while 
horizontal rails 76, 77, 78 and 79 (referred to as the left rail above) 
are joined only with other horizontal rails. As described above, the slide 
pads are shaped differently depending on whether they are mounted on a 
multi-planar rail or a horizontal rail. The slide pads may be square in 
shape, and are usually symmetrical with respect to their diagonal 
extending towards the center of the intersection when rails of identical 
shape are joined. 
FIG. 14 is a perspective view showing how a slide pad may be fastened to 
the track of the invention. Slide pad 98 may be secured to track 
intersection 80 by screw 81. The screw is placed through screw hole 82 
drilled through track 80. Rotation of slide pad 79 around screw hole 82 
may be prevented by placing lug (not shown) on the slide pad into a second 
hole 83 drilled through track 80. 
FIG. 15 is a detail of a slide pad of the invention for use on track 
corners where slanted rails intersect. The upper surface includes a 
horizontal portion 84 for engaging the outer drive wheel, and a slanted 
portion 85 for engaging the inner drive wheel. The lower surface also has 
a horizontal surface 86 to fit the horizontal planar portion of the rail, 
and a slanted surface 87 to fit the inner slanted surface of the rail. The 
pad also includes hole 90, which is capable of receiving a screw or other 
fastener to secure the pad to the track. Screw receiving wall 89 and lug 
88 also serve to prevent the lug from moving on the track. 
FIG. 16 is a detail of a slide pad of the invention for use on track 
corners where horizontal rails intersect. The entire lower surface 92 and 
94 of the pad is horizontal. Upper surface portion 91 is also horizontal 
to provide support of the outer drive wheel, while upper surface portion 
93 is slanted to support the slanted inner drive wheel. The pad also 
includes hole 96, which is capable of receiving a screw or other fastener 
to secure the pad to the track. Screw receiving wall 95 and lug 97 also 
serve to prevent the lug from moving on the track. 
Although the present invention has been described with reference to the 
accompanying drawings, it is not limited to that precise embodiment, and 
various changes and modifications can be effected therein without 
departing from the scope or spirit of the invention.