U.S. patent application number 09/761457 was filed with the patent office on 2001-05-31 for suspension and drive mechanism for multi-surface vehicle.
This patent application is currently assigned to A.S.V., Inc.. Invention is credited to Hetteen, Edgar, Lemke, Brad, Lemke, Gary, Safe, Cary.
Application Number | 20010001993 09/761457 |
Document ID | / |
Family ID | 22050819 |
Filed Date | 2001-05-31 |
United States Patent
Application |
20010001993 |
Kind Code |
A1 |
Lemke, Gary ; et
al. |
May 31, 2001 |
Suspension and drive mechanism for multi-surface vehicle
Abstract
A tracked vehicle produces a pressure no more than 3 psi on the
ground by increasing the number of contact points on the inner
surface of the track. The stiffness of the track is also selected
to minimize bowing between the idler wheels or rollers. The track
is therefore kept substantially straight between the rollers so
increase the efficiency associated with transferring power to
track. The drive sprocket is positioned above the ground so as to
eliminate complexity in the design and yet effectively transmit
power to the tracks. Positioning the drive sprocket above ground
also prevents derailing of the track. The track is also held in a
constant state of tension on the driver sprocket and the roller.
This too prevents derailment. The undercarriage of the vehicle
includes torsion axles and sealed bearings to provide for a lower
maintenance track. Components associated with the undercarriage do
not require constant greasing and cleaning of the idler wheels. The
track is beveled so that it does not rip up surfaces. The drive
sprocket is provided with roller sleeves that accommodate the
changes in the pitch line of an elastomeric flat track. The
sprocket does not "scrub" the areas between the driving lugs. The
drive sprocket includes a pair of scrapers and a pair of conical
shields which provide self cleaning and which remove debris from
the sprocket area.
Inventors: |
Lemke, Gary; (Grand Rapids,
MN) ; Lemke, Brad; (Grand Rapids, MN) ; Safe,
Cary; (Grand Rapids, MN) ; Hetteen, Edgar;
(Grand Rapids, MN) |
Correspondence
Address: |
SCHWEGMAN, LUNDBERG, WOESSNER & KLUTH, P.A.
P.O. Box 2938
Minneapolis
MN
55402
US
|
Assignee: |
A.S.V., Inc.
|
Family ID: |
22050819 |
Appl. No.: |
09/761457 |
Filed: |
January 16, 2001 |
Related U.S. Patent Documents
|
|
|
|
|
|
Application
Number |
Filing Date |
Patent Number |
|
|
09761457 |
Jan 16, 2001 |
|
|
|
09063685 |
Apr 21, 1998 |
|
|
|
Current U.S.
Class: |
180/9.5 |
Current CPC
Class: |
B62D 55/24 20130101;
B62D 55/10 20130101 |
Class at
Publication: |
180/9.5 |
International
Class: |
B62D 055/00 |
Claims
What is claimed is:
1. A vehicle for traversing a surface comprising: a flat track
further comprising: an inner surface, said inner surface including
a plurality of driving lugs; and an outer surface having a pattern
for gripping; a driver sprocket for said track, said driver
sprocket engaging at least some of said plurality of driving lugs;
a plurality of wheels in contact with the inner surface of the
track as the track engages the surface, said plurality of
substantially solid wheels spaced such that flexing of the track is
minimized between each of the wheels of said plurality of wheels in
contact with the track while the track contacts the surface as the
vehicle traverses the surface.
2. The vehicle of claim 1 wherein the driving lugs on the inner
surface of the track are aligned, and said plurality of wheels are
aligned so that the driving lugs pass between the wheels in contact
with the inner surface of the flat track.
3. The vehicle of claim 1 wherein the wheels are mounted on
axles.
4. The vehicle of claim 3 wherein each axle includes at least two
wheels.
5. The vehicle of claim 1 wherein the driving lugs are formed into
two aligned rows on the inner surface of the track, and said
plurality of wheels are aligned so that the driving lugs pass
between the wheels in contact with the inner surface of the flat
track.
6. The vehicle of claim 5 wherein each axle includes at least three
wheels, said axle including a sealed bearing.
7. The vehicle of claim 1 wherein the flat track includes
rubber.
8. The vehicle of claim 7 wherein the flat track further comprises
layers of flexible strengthening material incorporated with the
rubber.
9. The vehicle of claim 7 wherein the flat track further comprises
fiberglass rods encased by flexible strengthening material
incorporated with the rubber.
10. The vehicle of claim 1 wherein the flat track has beveled
edges.
11. The vehicle of claim 1 further comprising an track idler,
wherein the driver sprocket and the track idler remain in a
substantially fixed position with respect to the flat track.
12. The vehicle of claim 11 wherein the pattern for gripping
associated with outer surface of the track comprises: a first rib
crossing at least a portion of the outer surface of the track; and
a second rib crossing at least a portion of the outer surface of
the track, said first rib and said second rib spaced so that the
first rib moves toward the second rib to grip the surface the
vehicle is traversing, said first rib moving toward the second rib
after the track passes over the idler sprocket.
13. The vehicle of claim 1 wherein the driver sprocket for driving
the track is located remote from the portion of the track in
contact with the surface traversed by the vehicle.
14. The vehicle of claim 13 wherein the driver sprocket for driving
the track is located toward the rear of the vehicle.
15. The vehicle of claim 1 wherein the driver sprocket further
includes a plurality of rotatable sleeves for driving the driving
lugs associated with the track.
16. The vehicle of claim 1 wherein the driver sprocket is
substantially cylindrical in shape and has a substantially curved
inner portion, said vehicle further comprising a scraper positioned
near the substantially curved inner portion of the driver sprocket
to remove debris from the driver sprocket.
17. The vehicle of claim 1 further comprising torsion axle
suspension units attached between the vehicle frame and the
wheels.
18. The vehicle of claim 17 wherein the torsion axle comprises: a
first solid axle portion; a second tubular portion, the first solid
axle portion fitting within the second tubular portion; and an
elastomeric portion fitting within the spaces between the first
solid axle and the second tubular portion.
19. A drive sprocket comprising: a sprocket driver having a
transmission therein; a central drive plate attached to said
sprocket driver; a first annular ring attached to the central drive
plate; and a second annular ring attached to the central drive
plate.
20. The drive sprocket of claim 19 wherein the sprocket driver is
located more than one foot above the ground.
21. The drive sprocket of claim 19 wherein a plurality of shafts
are used to attach the first annular ring and the second annular
ring to the central drive plate.
22. The drive sprocket of claim 21 further comprising rotatable
sleeves positioned over the shaft portion between the first annular
ring and the central drive plate, and over the shaft portion
between the second annular ring and the central drive plate.
23. The drive sprocket of claim 19 further comprising: a first
scraper extending into the space between the sprocket driver and
the first annular ring; and a second scraper extending into the
space between the sprocket driver and the second annular ring.
24. A drive system for driving a vehicle over a surface comprising:
a flat track having an inner surface and an outer surface; driving
lugs attached to the inner surface of the flat track; a driver for
driving against the driving lugs, said driver positioned above the
surface over which the vehicle is driven.
25. The drive system of claim 24 wherein the flat track is held in
substantially constant tension.
26. The drive system of claim 24 further comprising: a first end
roller; and a second end roller, said driver, said first end roller
and said second end roller fixed with respect to the flat track
such that the flat track is held in substantially constant
tension.
27. A suspension mount comprising: tubular stock having a
substantially square cross section; and a bar having substantially
square cross section, the length of the diagonal on the bar being
less than the distance across the inside tubular stock so that the
bar may be positioned within the tubular stock; and elastomeric
elements positioned between the bar and the tubular stock.
28. The suspension mount of claim 27 wherein the elastomeric
elements are rubber cording.
29. The suspension mount of claim 27 wherein the elastomeric
elements are rubber cording, said rubber cording positioned in the
corner areas of the substantially square stock.
30. A set of wheels comprising: a shaft; an axle having wheels
attached thereto, said axle having an opening therein having a
diameter greater than the shaft; and a bearing for rotatably
attaching the axle to the shaft.
31. The set of wheels of claim 30 wherein the axle further
comprises a flange attached to the outside of the axle, at least
one wheel attached to said flange.
32. The set of wheels of claim 31 wherein the wheel attached to the
flange is split.
33. The set of wheels of claim 30 wherein the bearing is sealed.
Description
FIELD OF THE INVENTION
[0001] The invention relates to a multi-surface vehicle, and more
particularly to the suspension and drive mechanism associated with
a multi-surface vehicle with a rubber track.
BACKGROUND OF THE INVENTION
[0002] A variety of track driven vehicles have been around for many
years. Tracked vehicles vary from 100 ton military tanks and
bull-dozers to 300 pound snowmobiles. Track types vary from
segmented steel tracks to one piece molded rubber tracks.
[0003] One of the major design challenges with all types of tracks
and vehicles is to find the most efficient way to transfer the
torque of the drive mechanism to the track with minimum power loss.
There are many torque transmission systems. The three most common
torque transmission systems are an external drive, a friction drive
and an internal drive. External drives include a sprocket with a
fixed number of teeth around the circumference that drives against
a rigid member attached to the track. The sprocket teeth protrude
through the track to a point where the rigid members can not slip
back under a heavy load. Friction drives include a wheel attached
to the drive axle and drive against the inside surface of a track.
The outside of the wheel and the inside of the track are typically
made of resilient material such as rubber or other composites. The
track tension must be extremely tight to prevent slippage. The
track tension also results in power loss. Internal drive systems,
also known as involute drives, have a track with drive lugs
attached to the inside surface of the track. The drive lugs may be
molded to the inside surface of a rubber track. The drive sprocket
is made by attaching rigid drive teeth to a rigid radius wheel. The
sprocket teeth drive against the internal drive lugs on the
track.
[0004] Internal drive systems are generally considered the most
efficient drive for tracks made of elastomeric material such as
rubber when the drive lugs and drive sprockets are properly
matched. They are properly matched when the pitch diameter of the
sprocket matches the pitch line of the track. Another way of
determining whether they are properly matched is when the pitch
diameter of the sprocket causes the drive teeth to match perfectly
with the center to center distance between the track drive lugs. In
practice, proper matching is difficult to achieve especially when
using an elastomeric or rubber track. Tracks made of elastomeric
materials are resilient. As a result, the elastomeric material
stretches or contracts slightly depending on a number of factors.
One of the more common factors that causes changes in the pitch
length is the variation in the load applied to a track during
operation of the multi-surface vehicle. The load on the track and
on the internal lugs will be higher when the vehicle is pulling a
log as compared to the load on the track applied to merely move the
vehicle over terrain. The tracks may be loaded differently when
turning. An outside track will typically be loaded to a higher
degree when compared to an inside track. The pitch length of the
track varies with the variations in the load applied to the
track.
[0005] Variations in the pitch length of the track results in a
mismatch between the pitch length of the track and the pitch
diameter of the sprocket. When using a sprocket having rigid drive
teeth, the change in the pitch length along the track causes the
sprocket teeth to "scrub in" or "scrub out" or both. In other
words, the rigid tooth is rubbing between the individual drive lugs
on the internal surface of the flat belt. This causes a loss in
efficiency. Scrubbing in or out can result in extreme power loss
and excessive wear on the track drive lugs and sprocket teeth.
[0006] Another common problem with flat tracks such as those made
from an elastomeric material is that foreign matter or sticky
material builds up in the sprocket area. Metal tracks usually have
openings through which at least some foreign matter may be passed.
The buildup is worse on a flat track. When foreign matter builds up
in the sprocket area the pitch diameter or the pitch line of the
flat track is likely to change. This results in power loss and
excessive wear. Rocks, sticks, grass, mud, snow and other materials
may build up in the sprocket area.
[0007] Military tanks and bull-dozers are two common vehicles
featuring metal tracks. Metal tracks are typically mounted on drive
wheels and idler wheels that are mounted on springs or suspension
systems that allow the drive wheel to move slightly from a fixed
position. The use of rollers on the track drive segments of a metal
track reduces noise and reduces wear between the individual
segments of the metal track. The springs or suspension associated
with the idler wheels allows the metal track to accommodate
obstacles encountered by the metal track. At the drive wheels, the
springs also accommodate slight variations in pitch diameter.
[0008] Metal tracked vehicles have many problems. One of the
problems is that metal tracked vehicles are very heavy and tend to
sink in and damage relatively soft surfaces. The pressure produced
by a metal tracked vehicle is relatively high. For example, when a
metal tracked vehicle operates in mud, the vehicle typically sinks
to solid ground rather than passing over such a surface. The tracks
also are tough on surfaces such as grass or lawns. The pressure
produced by the metal track of a bull-dozer or a tank typically
produces indentations in a surface. For example, if a bull-dozer
passes over a residential lawn, the pressure is high enough to
compact the earth and form a permanent indentation. A home owner
would have to fill in the impressions with additional soil to fix
the lawn. In addition, the metal tracks typically have square edges
which dig into surfaces during turns. A turning bull-dozer would
rec havoc with residential lawns. Metal tracks can also become
derailed.
[0009] Some tracked vehicles have used rubber tracks. Typically,
designers of metal tracked vehicles carry over many of the design
characteristics into flat track vehicles using elastomeric or
rubber tracks. Many of the problems encountered with metal tracks
are also encountered with rubber tracks. For example, many rubber
track designs include a track mounted on drive wheels or sprockets
which are spring mounted. The problem of matching the pitch line of
the track to the pitch diameter of the sprocket is further
exacerbated. The drive wheels do not maintain the track near a
constant state of tension so the pitch line can fluctuate
widely.
[0010] In addition, the drive sprocket is positioned so that it in
contact with the surface. Typically, the drive sprocket will be at
the rear of the vehicle and positioned so that the track passes
between the drive wheel and the ground. In such designs, the rear
drive wheel has two jobs. The rear drive wheel drives the track and
maintains the alignment of the track. When the rear drive wheel is
on the ground, the two jobs the rear drive wheel is called on to do
work against one another. When driven, the track tends to want to
leave the drive wheel or "jump off the sprocket". It is necessary
to maintain alignment to prevent derailing. Rear drive wheels on
the ground are more prone to derailing since the forces associated
with doing the two jobs counteract one another. Another problem
with rear drive wheels on the ground is that they tend to require
additional complexity. Elongated gear boxes must be used to
transfer power to these rear on the ground drive wheels.
[0011] Another problem associated with flat elastomeric tracked
vehicles is that there are few idler wheels that contact the
ground. The track tends to bow between the idler wheels which
results in a loss of traction. In addition, with fewer points on
the ground and bowing between the wheels, the effective surface
pressure at various points under the wheels is high. The tracked
vehicle does not have an even pressure across the flat track. Still
another problem is that these vehicles are high maintenance. Each
individual wheel must be greased periodically. In addition, since
the environment for use includes foreign matter such as dirt, the
individual idler wheels tend to wear. Because of the high
maintenance and cost, there is a tendency to use lesser numbers of
wheels in various designs.
[0012] As a result of high pressure per wheel, most designs of
tracked vehicles using elastomeric or steel tracks are not
environmentally friendly. Current designs still indent soft
surfaces and tear up grass lands. In addition, the current vehicles
are high maintenance. High maintenance is needed to assure that the
components of the undercarriage do not prematurely wear.
[0013] Thus, there is a need for a for a tracked vehicle that
produces a low pressure on the surface and which is environmentally
friendly. In addition, there is a need for a lower maintenance
vehicle not prone to derailing the track. In addition, there is a
need for a vehicle which has many contact points, and therefore has
lower pressure per wheel, on the track as it passes over the
surface. There is also a need for a vehicle which does not require
constant greasing and cleaning of the wheels in contact with the
track. There is also a need for a vehicle which places the drive
sprocket off the ground so as to eliminate complexity in the design
and yet effectively transmit power to the tracks. In addition,
there is a need for a sprocket which will accommodate the changes
in the pitch line of an elastomeric flat track. In addition, there
is a need for a sprocket which will not "scrub" between the driving
lugs. There is also a need for a sprocket which is self cleaning
and which removes debris from the sprocket area to minimize
problems associated with debris build up changing the pitch
relationship between the sprocket and the flat track.
SUMMARY OF THE INVENTION
[0014] A tracked vehicle produces a pressure no more than 3 psi on
the ground and less than 190 pounds per contact point on the inner
surface of the track. Multiple wheels across the width of the track
eliminate bowing between the idler wheels or rollers. The track is
therefore kept substantially straight across the rollers to
increase the efficiency associated with transferring power to
track. The drive sprocket is positioned above the ground so as to
eliminate complexity in the design and yet effectively transmit
power to the tracks. Positioning the drive sprocket above ground
also prevents derailing of the track. The track is also held in a
constant state of tension on the driver sprocket and the roller.
This too prevents derailment. The undercarriage of the vehicle
includes torsion axles and sealed bearings to provide for a lower
maintenance track. Components associated with the undercarriage do
not require constant greasing and cleaning of the idler wheels. The
track is beveled so that it does not rip up surfaces. The drive
sprocket is provided with roller sleeves that accommodate the
changes in the pitch line of an elastomeric flat track. The
sprocket does not "scrub" the areas between the driving lugs. The
drive sprocket includes a pair of scrapers which provide self
cleaning and which remove debris from the sprocket area.
[0015] Advantageously, the vehicle will travel over soft surfaces
without causing damage to the surface. In addition, unlike other
vehicles, the vehicle sinks little in soft mud or snow. The
resulting vehicle is very effective in transmitting power to the
surface over which it passes. The vehicle requires very low
maintenance since the bearings associated with the undercarriage
are sealed. Other suspension units are simple and straightforward
and require little or no maintenance. The vehicle also is less
prone to track derailment.
BRIEF DESCRIPTION OF THE DRAWINGS
[0016] The following detailed description of the preferred
embodiments can best be understood when read in conjunction with
the following drawings, in which:
[0017] FIG. 1 is a side view of the multi-surface vehicle.
[0018] FIG. 2 is perspective view of the undercarriage of the
multi-surface vehicle.
[0019] FIG. 3 is perspective view of the rubber track used with the
multi-surface vehicle.
[0020] FIG. 4 is a top view of the track showing the tread
pattern.
[0021] FIG. 5 is a cross-sectional view along line 5-5 in FIG.
4.
[0022] FIG. 6 is a cross-sectional view along line 6-6 in FIG. 4
showing the idler wheels in phantom engaging the lugs of the
track.
[0023] FIG. 7 is an exploded perspective view showing multiple
wheels attached to a single tubular axle having multiple wheels and
sealed bearings.
[0024] FIG. 8 is a perspective view of an axle 710 and the wheel
plate.
[0025] FIG. 9 is a perspective view of the drive sprocket which
engages the drive lugs on the track and a scraper.
[0026] FIG. 10 is a cross-sectional view showing the suspension
unit, also called the rear torsion axle and swing joint.
[0027] FIG. 11 is a partial perspective view of the undercarriage
of the multi-surface vehicle as it engages an obstacle on the
surface being traversed.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
[0028] In the following detailed description of the preferred
embodiments, reference is made to the accompanying drawings which
form a part hereof, and in which are shown by way of illustration
specific embodiments in which the invention may be practiced. It is
to be understood that other embodiments may be utilized and
structural changes may be made without departing from the scope of
the present invention.
[0029] FIG. 1 shows a perspective view of a multi-surface vehicle
100 on a surface 110. The multi-surface vehicle 100 includes a
frame 102 which carries an engine 120 such as an eighty horsepower,
4.5 liter John Deere PowerTech Diesel or a one hundred fifteen
horsepower, 4.5 liter John Deere PowerTech Turbo Diesel. Both of
these engines are available from John Deere and Company of Moline,
Ill. The engine 120 powers a hydrostatic transmission which powers
hydraulic drive motors with planetary gear boxes which eliminates
additional chains and sprockets, thereby lessening the complexity
and increasing the efficiency of the drive system. Two auxiliary
pumps are used to power different accessories. As shown, the
vehicle includes a loader/bucket accessory 130. The engine 120
powers hydraulic pumps used to drive the hydraulic cylinders 132
and 134 for operation of the loader 130. Other accessories, such as
a blade or logging device may be substituted for the loader 130.
The vehicle 100 also includes an operator cab 140. The operator cab
is equipped with controls for controlling the loader 130 and for
operating the multi-surface vehicle 100. Attached to the frame 102
of the multi-surface vehicle 100 is an undercarriage 200. A
duplicate undercarriage is attached to the other side of the frame
102. The undercarriage 200 is attached to the frame 102 via torsion
axle type suspension units 1000. The undercarriage 200 includes a
drive sprocket 900 for driving a flat elastomeric or rubber track
300. It should be noted that the drive sprocket 900 is positioned
off the surface 110 so that it will stay clean for a longer life.
The undercarriage 200 features multiple idler wheels 700 on axles
(shown in FIG. 2) which engage the inner portion of the track 300
as the track engages the surface 110. The wheels 700 are of a
selected diameter and spaced so that track 300 will not bow between
the contact points as the track travels over the surface 110. The
properties of the elastomeric track 300 also are selected so that
the track has a sufficient stiffness so that the track 300 stays
substantially straight between the contact points of the various
idler wheels 700. As shown in FIG. 1, eight different axles
carrying wheels 700 are shown in contact with the track 300. The
wheels 700 provide multiple contact points which more evenly
distribute the weight of the vehicle 100 and its load over the two
tracks 300. By keeping the individual tracks 300 substantially
straight between the various contact points, the track 300 is also
better able to grip the surface 110.
[0030] FIG. 2 is perspective view of one side of the undercarriage
200 of the multi-surface vehicle 100. The As can be seen from this
view, there are two frame members 202 and 204 which are part of the
frame 102 of the vehicle 100. The undercarriage 200 includes an
undercarriage frame 210 which includes an upper portion 212 and a
side skirt 214. Attached to the upper portion 212 of the
undercarriage frame 210 are cross members 220, 222, and 224. The
cross members include a channel each of which accommodates a
suspension unit or torsion axle 1000. The torsion axle type
suspension unit 1000, which will be described in more detail in
FIG. 9, provides an essentially maintenance free suspension member
which does not require greasing or regular cleaning. Attached to
each end of a cross member is a wheel plate 230 and a wheel plate
232. The wheel plates for cross member 222 are described here. For
the sake of clarity, the other wheel plates are not numbered. The
other wheel plates are attached to cross members 220 and 224 are
substantially identical to the wheel plates 230 and 232 attached to
cross member 222. Each wheel plate carries two wheel axles 710 and
712. Each wheel axle carries three wheels 700. The wheels 700 have
a rubber or plastic outer annulus 702 attached to a central wheel
704 made of either plastic or metal. The outer annulus provides for
enhanced contact with the flat track or belt. The wheels 700
attached to first end axle 714 and to second end axle 718 are fixed
with respect to the undercarriage frame 210. The end axles 714 and
718 are actually in a fixed position in a notch in the side skirt
214 of the undercarriage frame 210.
[0031] Also attached to the undercarriage frame 210 at a position
above the end axle 718 is the drive sprocket 900. The drive
sprocket 900 is in a fixed position with respect to the
undercarriage frame 210. It should be noted that the wheels on the
end axle 714, the wheels on the end axle 718, and the drive
sprocket 900 are all in fixed position with respect to the
undercarriage frame 210. These particular wheels and the drive
sprocket 900 define the outer limits of the flat track 300. It is
important to have a fixed position for these wheels and the drive
sprocket 900 so that the elastomeric track 300 is held in a
substantially constant state of tension. The pitch length of an
elastomeric track, such as those made of rubber, will vary
slightly. The pitch length will stretch slightly as variable loads
are applied to the track 300. The use of springs or other
suspension means at these points will allow for the track to
collapse inward too much when a load is placed on the track 300.
Springs or other suspension means, commonly used to keep metal
tracks, will allow the elastomer tracks to dislodge or come off.
Therefore, it is imperative that no springs or anything are used to
maintain the tension on the track.
[0032] As can be seen, the wheels 700 provide for a plurality of
contact points onto the internal surface of the track. In fact the
eight axles each having 3 wheels provide for a total of 24 contact
points to the internal surface of the flat track 300. The vehicle
has a duplicate undercarriage on the other side of the vehicle. The
end result is at any given time there is approximately 2,844 square
inches in contact with the ground or surface 110. Forty eight
wheels or contact rollers spread the weight evenly over the two
tracks 300 so that superior traction and flotation are achieved.
There is also a minimal amount of force at each contact point. The
ground pressure associated with the vehicle 100 is no more than 3
psi (pounds per square inch) which means that the vehicle has the
capability to work on soft ground or lawns without forming ruts or
compacting soil.
[0033] Of course to keep the soil from compacting or forming ruts,
the elastomeric track 300 is formed of a material which is stiff
enough such that it will not bow between the contact points of the
wheels 700. This the track 300 substantially flat and in contact
with the ground or surface 300.
[0034] FIG. 3 is perspective view of the elastomeric or rubber
track 300 used with the multi-surface vehicle 100. The track 300
has an outer surface 310 which has a tread pattern 312. The track
300 also has an inner surface 320. Attached or molded to the inner
surface of the track 300 are a plurality of drive lugs 322. The
drive lugs 322 are arranged in two rows 330 and 332. The spacing
between the rows 330 and 332 is selected so that the width of the
middle wheels on a three wheel axle fits between the first row 330
of drive lugs 322 and the second row 332 of drive lugs 322.
Typically approximately one-half inch of clearance is provided so
that the track 300 can shift an appropriate amount during a turn or
other operation. The outer wheels 700 fit between one row of lugs
322 and the outer edge of the track 300. The spacing from one lug
322 to another within a row is selected so that the lugs 322 will
properly engage the sprocket 900. Proper engagement would match the
pitch diameter of the drive sprocket 900 to the pitch line of the
track 300. Of course, this is difficult to achieve since there are
different forces on the track 300 at various times.
[0035] FIG. 4 is a top view of the outer surface 310 of a section
of the track 300 showing the tread pattern 312. The tread pattern
312 includes a series of transverse grooves 340, 341, 342, 343, and
344. The tread pattern 312 also includes a first beveled edge 314
and a second beveled edge 316. The beveled edges 314 and 316 allow
some side-to-side movement which accommodates turns made with the
elastomeric or rubber track 300. The allowance of the side-to-side
motion from turning makes for a very environmentally friendly
track. Unlike square tracks that typically dig into the ground and
produce track damage, the beveled edges 314 and 316 on the track
300 can slip over the ground during a turn to leave the terrain
substantially undamaged. The transverse grooves 340, 341, 342, 343,
and 344 are at a selected spacing and at a selected depth so as to
leave ribs between the grooves. The ribs formed between the grooves
340, 341, 342, 343, and 344 are dimension so that after the track
passes over the wheels 700 associated with the end axle 714 and
into contact with the ground, the ribs close and grip the
vegetation or the ground surface 110 for added traction.
[0036] FIG. 5 is a cross-sectional view along line 5-5 in FIG. 4.
Both the inner surface 320 and the outer surface 310 of the track
are shown in this view. The track also includes stiffeners 350,
352, and 354. The stiffeners 350, 352 and 354 increase the
stiffeners of the track 300 across the width of the track 300. The
stiffeners 350, 352 and 354 are fiberglass rods which are molded
into the track. The stiffeners 350, 352 and 354 are placed in the
wider ribs such as those formed between grooves 341 and 342, and
formed between grooves 343 and 344. The driving lugs 322 are shown
molded or attached to the inner surface 320 of the track 300. The
distance between the lugs 322, depicted by the reference number 360
is selected so that the engaging portions of the drive sprocket 900
engages the portion of the inner surface 320 between adjacent lugs
322 in a row. Ideally, the "teeth" of the drive sprocket 322 would
engage the lugs 322 with little or no backlash or extra spacing
located between the lugs 322. This is difficult to achieve given
that the pitch of the elastomeric track 300 will stretch slightly
as a function of the load placed on the track 300.
[0037] FIG. 6 is a cross-sectional view along line 6-6 in FIG. 4.
The rollers or idler wheels 700 engaging the lugs of the track have
been added in phantom to FIG. 6. As can be seen, the rollers or
idler wheels 700 do not fit tightly with respect to the rows 330
and 332 of lugs 322. This allows for slight movement of the track
with respect to the wheels 700 attached to a single axle, such as
axle 710 (shown in FIGS. 2 and 7). The rows 330 and 332 are spaced
such that the wheels 700 of the undercarriage fit between the rows
330 and 332. The drive lugs 322 thus prevent the track from
dislodging or jumping off since the engaging drive lugs control or
stop the side-to-side motion of the track 300. The drive lugs 322
have beveled sides 323 and 324 which allow the beveled sides of the
multiple wheels to butt up against the tracks. Another aspect of
these driving lugs 322 is that the spacing on them allows the track
some lateral movement. The lateral movement enhances the
turnability of the vehicle 100.
[0038] One stiffener 350 is shown in FIG. 6. The stiffener 350 is
molded into the track 300 and is a fiberglass rod positioned
transverse to the path of travel. The transverse fiberglass rods
strengthen the track. The fiberglass rod 350 terminates well short
of the beveled edges 314 and 316 so as to prevent the stiffener 350
from releasing from the flat track 300. On other flat tracks, the
release of a fiberglass rod from the track was a precursor to track
failure. As a result, the fiberglass rod 350 is stopped well short
of the end of track 300 and then enveloped in five to seven layers
of Kevlar or another tire cording material. This prevents the
stiffener 350 from leaving the flat track 300 thereby forming a
weak spot in the track.
[0039] FIG. 7 is an exploded perspective view showing multiple
flanges 720, 721, 722, and 724 rotatably attached to a single
tubular axle 710. FIG. 8 shows an assembled axle and attached
wheels. Now turning to FIGS. 7 and 8, the idler wheels or rollers
700 are attached to a the flanges 720, 721, 722 and 724. There are
two types of rollers or idler wheels 700. The first type of roller
or idler wheel 700 is an outside wheel 702 which fits one of the
ends of the shaft 710. The second type of roller or idler wheel 700
is an intermediate wheel 704. The intermediate wheel 704 attaches
to flanges 721 and 722 intermediate the two ends of the wheel shaft
710. The intermediate wheel 704 comprises a first half 706 and a
second half 708. Each of the two halves 706 and 708 is split along
a diameter of the wheel 704 to form two semicircular halves. The
two semicircular halves 706 and 708 are bolted to the flange 722 on
the axle 710 to form an intermediate wheel 704. The outside wheels
702 and the intermediate wheel 704 form a circular plastic rim with
a rubber outer diameter. The plastic rims are bolted to the flanges
720, 721, 722, and 724. The outside wheels are provided with an
endcap 732 and an endcap 734.
[0040] The axle 710 is a hollow tubular element. The flanges 720,
722, and 724 are attached to the hollow tubular element. The axle
710 or hollow tubular element is mounted on a shaft 730. The shaft
730 has two ends which protrude from the ends of the hollow tubular
axle 710. The tubular axle 710 is rotatably attached to the shaft
730 by a first roller bearing set 750 and a second roller bearing
set 752. The entire inner portion of the axle is filled with oil or
grease. The roller bearings 750 and 752 are both sealed bearings.
The roller bearings 750 and 752 are provided with multiple seals so
that a sealed bearing for all three wheels 700 (shown in FIG. 8) is
formed. Use of a sealed bearing sharply reduces maintenance time
and keeps the life of the bearings high. Including three rollers or
idler wheels 700 on an axle 710 is less expensive to manufacture
and also provides for a maintenance free part that lasts up to the
life of the vehicle 100. Each end is provided with three seals. The
bearing has a first seal 760, an annular plastic or rubber element
that fits over one side of the bearings, which comes with the
bearing set. A second seal 762 is positioned outside of the bearing
set. A third seal 764 includes seven different seals in one. The
third seal 764 has a tortuous path to prevent dirt from getting
into the bearing or into the space between the axle 710 and the
shaft 730. If dirt or other contaminants get into the grease or the
oil covering the bearing sets 750 and 752, the life of the bearings
will be shortened. However, dirt entering through the first seal
760, the second seal 762 and the third seal 764 would have to pass
through nine seals in order to get to the lubricant. The rollers in
each of the bearing sets are in a cage. The roller cage and the
bearings are submersed in the oil or grease found within the hollow
tubular axle 710.
[0041] FIG. 8 shows the wheels 700 attached to the tubular axle
710. The single shaft 730 is shown protruding from the sealed end
of the tubular axle 710. The shaft 730 extends beyond the endcap
734. The shaft 730 includes a flat or keyway 740 that engages the
wheel plate 230. The wheel plate 230 includes an axle capture plate
231 which, when bolted to the wheel plate 230, captures the axle
730. Only one axle capture plate is shown in FIG. 8.
[0042] FIG. 9 is a perspective view of the drive mechanism
including the sprocket 900 which engages the drive lugs 322 on the
track 300. A first scraper 940 and a second scraper 942 are
positioned near the inner diameter of the drive sprocket to clear
the drive sprocket of debris that may otherwise accumulate. The
driver sprocket 900 includes a central drive plate 902. A number of
tubular elements 904 are welded or otherwise attached to the
central drive plate 902. Attached to the central drive plate is a
first annular unit 910 and a second annular unit 911. As shown, the
first annular unit 910 and a second annular unit 911 are attached
to the central drive plate 902 using a long bolt or pin 912. A set
of spacers 914 and 916 are used to define the spatial relationships
between the central drive plate 902 and the first annular unit 910
and the second annular unit 911. Spacers 914 and 916 also carry
roller sleeves 920 and 922. The roller sleeves roll with respect to
the spacers and with respect to the central drive plate 902. In
other words, the roller sleeves 920 and 922 fit between the drive
plater 902 and the first annular unit 910, and and between the
drive plater 902 and the second annular unit 911. The roller
sleeves 920 and 922 are dimensioned and spaced so that they can
engage the spaces between the drive lugs 322 on the inside portion
320 of the rubber or elastomeric track 300. The roller sleeves are
advantageous in that they are self adjusting. As the rubber track
passes over a roller sleeve 920 and 922, the pitch of the track 300
actually changes since the track is elastomeric. The roller sleeves
accommodate such changes in pitch since they can roll between the
drive lugs 322 rather than scrub the inner surface 320 between the
drive lugs 322. The end result is that the roller sleeves 920 and
922 also prevent chatter or extra vibrations at various speeds of
the track.
[0043] The drive plate 902 is attached to a sprocket driver 930.
The sprocket driver 930 is attached to portion of the frame of the
vehicle and which includes a first scraper 940. Also attached to
the sprocket driver 930 is a hydraulic pump 932. The hydraulic pump
is attached to a source of hydraulic fluid. As hydraulic fluid is
passed through the hydraulic pump 932 an output shaft 934 turns a
planetary transmission system housed within the sprocket driver
930. The central drive plate 902 is attached to an annular ridge
909 on the sprocket driver 930. A second scraper 942 is attached a
plate 907 which is attached to the undercarriage frame 210. The
sprocket driver 930 is attached to the plate 907. There are a
series seals and a cap 905 that prevents contamination of the
sprocket driver 930 with dirt or other contaminants.
[0044] The scrapers 940 and 942 force and remove the debris from
the drive sprocket 900 and deposit it outside the drive sprocket
900. This is critical since build up of debris within the sprocket
will generally tend to change the pitch line of the track further.
In addition, debris build up tends to act to dislodge or derail the
track 300 from the drive sprocket 900. The first scraper 940 and
the second scraper 942 are cantilevered in toward the central drive
plate 902 of the drive sprocket 900. The second scraper 942 is
cantilevered from another plate 907 that is typically attached to
the undercarriage frame 210. The first scraper 940 and the second
scraper 942 are positioned near the inner diameter of the rollers
920 and 922 of the driver sprocket 900. The scrapers 940 and 942
remove debris from the rollers and force the debris away from the
sprocket driver 930 and the track 310. The scrapers 940 and 942 are
cantilevered and stick into the inside diameter of the driver
sprocket 900. Without the scrapers 940 and 942, mud and other
debris would accumulate and eventually lift the track 300 from the
drive sprocket 900 to dislodge it from its operating position. The
scrapers 940 and 942 are arcuate in shape. By dislodging mud and
other debris from the driver sprocket 900 and placing the debris
elsewhere, the scrapers 940 and 942 keep the driver sprocket 900
clean and clear of mud or other debris.
[0045] The placement of the driver sprocket 900 enhances the
ability of the track to stay on or not become dislodged, when
compared to other vehicles. Now referring FIGS. 1, 2 and 9, the
driver sprocket 900 is placed off the ground or surface 110, and
toward the rear of the vehicle. Placing the driver sprocket above
the ground prevents derailing for several reasons. The force of the
driver sprocket 900 on the track tends to act to dislodge the track
300 from the driver sprocket 900. When the driver is on the ground,
not only is the driver sprocket driving the track 300, it is also
trying to maintain the alignment of the track. Thus, when the
driver sprocket 900 is on the ground the two jobs counteract one
another. In other words, the track is undergoing a force tending to
dislodge or derail the track 300 while also being used to keep the
track 300 aligned. Placing the driver sprocket 900 above the ground
removes the function of maintaining alignment. The above ground
driver sprocket's only function is to drive the track 300. In
addition, placing the driver sprocket 900 above ground and near the
rear of the vehicle prevents dislodgment of the track 300. In the
elevated position, the driver sprocket applies a large force to the
track at the last or rear axle carrying three roller or idler
wheels 700. The drive sprocket 900 pulls the track 300 into
alignment with the wheels associated with the rear axle thereby
keeping the track from being dislodged or coming off the rollers.
It should be noted that dislodgement or track derailing is very
costly and time consuming. Many times the track 300 is ruined or
damaged due as a result of being dislodged.
[0046] FIG. 10 is a cross-sectional view showing the axle mounting
bracket 1010 which uses a several suspension units also called a
torsion axle 1000. Each torsion axle 1000 is comprised of a shell
1020 of a length of square tubular material. An inner bar 1030
having a substantially square cross section is positioned within
the shell 1020. Rubber cords 1040 are placed between the shell 1020
and the inner bar 1030. The inner bar is placed on a diagonal with
respect to the inside square cross section of the tubular material
comprising the shell 1020. Within the square tubular stock of the
shell 1020, there is fitted a square cross-sectional piece of
rectangular stock referred to as the inner bar 1030. The inner bar
1030 has a diagonal which is slightly less than the shortest
dimension between the walls of the square tubular stock of the
shell 1030. The inner bar 1030 makes a diamond inside or is fitted
within the square tubular stock so that it looks like a diamond
within the perimeter of the square tubular stock shell 1020.
Positioned in the corners of the square tubular stock of the shell
1020 are four elastomeric cords or rubber cords 1040 which run the
entire length of the shell 1020.
[0047] This arrangement provides for a stiff suspension unit or
torsion axle that never requires lubrication and is therefore
maintenance free and very reliable. The torsion axles 1000 are used
throughout the undercarriage 200. Turning briefly to FIG. 2, the
x's shown in that figure depict attachments which use the torsion
axle 1000. For example, two wheel plates 230 and 232 carry two
axles 710 and 712. Each of the axles 710 and 712 have three wheels
attached thereto. The wheel plates are attached to one another via
a torsion axle 1000. The torsion axle 1000 is a stiff suspension
member used to attach two axles of three wheels a piece to the
undercarriage frame 210. The end result is an inexpensive, simple,
and straightforward suspension member that is impervious to dirt,
requires little or no maintenance, and which does not need to be
sealed.
[0048] FIG. 11 is a partial perspective view of the undercarriage
200 of the multi-surface vehicle 100 as it engages an obstacle 1100
on the surface 110 being traversed. The resulting amount of
stiffness produced by the torsion axles 1000 allows the wheels to
hug the ground 110 even when a rock or other obstacle 1100 is
encountered so as to keep more tread 312 of the track 300 on the
ground 110 at any given time. When an obstruction is not
encountered, the torsion axle 1100 is sufficiently stiff so that
the belt or rubber track maintains a substantially unbowed state
between the wheels 700 associated with the undercarriage 200.
[0049] Advantageously, the vehicle will travel over soft surfaces
without causing damage to the surface. In addition, unlike other
vehicles, the vehicle sinks little in soft mud or snow. The
resulting vehicle is very effective in transmitting power to the
surface over which it passes. The vehicle requires very low
maintenance since the bearings associated with the undercarriage
are sealed. Other suspension units are simple and straightforward
and require little or no maintenance. The vehicle also is less
prone to track derailment.
[0050] Although specific embodiments have been illustrated and
described herein, it is appreciated by those of ordinary skill in
the art that any arrangement which is calculated to achieve the
same purpose may be substituted for the specific embodiments shown.
This application is intended to cover any adaptations or variations
of the present invention. Therefore, it is manifestly intended that
this invention be limited only by the claims and the equivalents
thereof.
* * * * *