Amphibious vehicle with improved track securement and guide means

A multi-pontoon amphibious vehicle with an improved track securement and guide means for the track to prevent "track throw" or loss and minimize wear while operating at speeds of up to twenty miles per hour. The vehicle includes two spaced-apart parallel pontoons joined by a centrally located operator's platform structure, with each pontoon having a moveable endless cleated track for propulsion, with the track supported on its pontoon by fore and aft multiple sprocket wheel sets and a series of larger bogie wheels at its botton and guides at its top. Each track comprises a parallel set of continuous endless belts carrying a series of laterally disposed cleats with drive lugs, which lugs are engaged by the teeth of four sprockets wheels per track.

BACKGROUND OF THE INVENTION: 
1. Field of the Invention: 
The present invention relates to an amphibious, all terrain type vehicle 
(ATV), namely a marsh or swamp craft of the type having two spaced-apart 
elongated pontoons, and more particularly to an improved tracked 
amphibious marsh vehicle utilized for travel over different types of 
terrain, such as swamps, marsh and the like, and for travel cross-country 
with obstacles of different character, with various degrees of inclination 
and at relatively high operating speeds of, for example, twenty miles per 
hour. 
2. General Background 
Various amphibious craft and all terrain vehicles are known in the art. One 
commonly known and cited is U.S. Pat. No. 2,546,523, issued March 27, 
1951, to Reynolds. The Reynolds patent describes a marsh buggy vehicle 
with a pair of spaced, elongated pontoons disposed and secured in a 
parallel relationship, two endless roller chains passing about each 
pontoon over sprockets mounted on transverse, driven shafts. The chains 
are joined together transversely by slats which form the treads or cleats 
for the craft. This type of marsh craft having spaced pontoons have 
enjoyed substantial commercial success as personnel carriers, and 
supporting working "uppers", such as draglines for construction of 
ditches, levees, etc. in a marsh environment. The spaced-apart, tracked 
pontoons enable the vehicle to turn easily, in a manner comparable to 
land-based tracked vehicles such as bulldozers and tanks, for example. 
However, the pontoons provide buoyancy to allow the vehicle to float when 
crossing open water. 
An improved example of the Reynolds type of pontoon marsh vehicle is shown 
in U.S. Pat. No. 3,842,785, issued Oct. 22, 1974, to Rivet. The Rivet 
apparatus included two connected pontoons, with two endless drive chains 
carried in channels disposed on top and bottom of each pontoon. Cleats 
attached to the chains have plastic blocks which are secured to the web of 
the cleats and which are positioned to bear against the top and bottom of 
the pontoons such as when the machine hits a tree stump, thus preventing a 
bending of the cleats. A series of spaced, transverse I-beams and 
bulkheads in the bottom of the pontoon hull reinforced the pontoons for 
work in a treed swamp environment. 
These and other similar vehicles using spaced-apart pontoons and roller 
chain have a number of operating problems, the most common of which is 
roller chain wear. In operation, the chain is exposed to abrasive mud and 
sand as well as water. In order to prolong the chain life, it is a common 
practice to lubricate the elements of the chain in places of connection. 
Any lubricant applied to a chain has a tendency to catch and collect dirt 
and sand, which causes rapid wear of the chain elements, particularly 
between the carrier roller and pin. Roller chain experiences substantial 
heat build-up at speeds greater than a few miles per hour (eg. 0-5 mph). 
Thus, roller chain machines are generally slow moving dinosaur-like 
monsters, typically most effective as work oriented machines supporting a 
crane, dragline, backline or the like where speed is a minimal need. 
Some inventors have used rubber belts instead of metal chains, as for 
example in U.S. Pat. No. 3,217,687, issued Nov. 16, 1965, to Erkelson et 
al., which describes vehicle having a float-like body above the tracks 
provided for operation mainly in water when the drive belts are 
substantially submerged. 
But some vehicles face another problem when traveling on the ground, this 
problem being commonly known as "chain throw" or "track throw," which 
arises from the inability of many such designs to provide efficient means 
for securing a chain or a belt in its place over the driving sprockets or 
wheels. 
Additionally, many "marsh buggies" have had the problem of "track sag," 
which further adds to the problem of track throw. 
These problems have been known in the art for along period of time and, to 
prevent rapid wear of the elements, a number of solutions have been 
suggested. In some cases, special pads are attached to the sides of a 
chain in order to reduce friction and thus to eliminate the problem. While 
these and other solutions have proven to be satisfactory to some extent, 
they sill have not provided full reliability. 
A recent patent directed to an improved tracked, amphibious vehicle with 
track securement and guide means is U.S. Pat. No. 4,433,634, issued to 
John B. Coast, applicant herein. The Coast '634 patent provides a pontoon 
type amphibious vehicle using bogie wheels and an endless driven belt. The 
belt carries cleats and sprockets drive the belts. A belt retention system 
includes lugs on the inner surface of the belts which are located to 
prevent the belt from moving off its longitudinal center by engaging the 
inner surface of the bogie wheels. The present invention provides an 
improvement to the vehicle shown and described in the Coast U.S. Pat. No. 
4,433,634 which is incorporated herein by reference. 
Other prior patents showing exemplary amphibious type vehicles are listed 
below: 
______________________________________ 
U.S. Pat. No. Patentee(s) Issue Date 
______________________________________ 
2,068,664 J. A. Dorst 01/26/37 
2,404,489 J. M. Hait 07/23/46 
2,487,397 B. A. Swennes 11/08/49 
3,108,564 H. L. Prosser 10/29/63 
3,299,849 A. H. Pitchford 
01/24/67 
3,418,961 F. B. Gregg 12/31/68 
3,474,751 M. E. Hebert 10/28/69 
3,487,802 L. H. Roy 01/06/70 
3,611,979 M. E. Hebert 10/12/71 
3,760,763 A. V. Brusacoram 
09/25/73 
______________________________________

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
FIGS. 1 and 2 provide overall side and rear elevational views of the 
preferred embodiment of the apparatus of the present invention designated 
generally by the numeral 10. Amphibious craft 10 has a pair of spaced 
apart elongated longitudinally extending pontoons 11, 12 connected by a 
central platform 13 formed of I-beams, channel beans, or other structural 
metal framing members for example. Pontoons 11, 12 include a generally air 
tight closed wall structure defined by side walls 11A, 12A and 11B, 12B 
and Top walls 11C, 12C and bottoms 11D, 12D. The platform 13 carries an 
engine or like power source 14 and can have a personal area or cabin 15 
with one or more seats 16. A tiller 17 steers the vehicle 10. A roll cage 
18 protects the operator (not shown) and the engine 14 during rollover, 
and from brush during transit through thick underbrush. The power source 
14 drives a pair of hydrostatic transmissions 19, 20 that connect via gear 
reducers 21, 22 or like means respective to left and right drive shafts 23 
which carry drive sprockets 25 A,B,C,D. 
A series of longitudinally spaced bogie wheels 30 support the vehicle, the 
wheels 30 being rotatably mounted upon shafts 34 at the bottom area of 
each of the pontoons 11, 12 in position on opposite respective sides of 
the longitudinal centerline of the pontoon as shown in FIG. 4. Wheels 55 
mounted upon shafts 24 are used as take up idlers for tracks 27, 28 at the 
top respective front portions of each pontoon 11, 12 (FIG. 5). 
A moveable continuous endless track 27, 28 is provided for each pontoon 11, 
12 respectively, each track 27, 28 encircling its respective pontoon 11, 
12 in tracking engagement with the plurality of bogie wheels 30 supplied 
to each pontoon 11, 12 and positioned on both sides of each pontoon 11, 12 
centerline 26. Each track 27, 28 can be in the form of a pair of 
reinforced rubber belts 27A, 27B (FIG. 4) ground engaging cleats 29 are 
carried by the tracks 27, 28 for providing traction of the vehicle 10 as 
the endless tracks 27, 28 move with respect to the pontoons 11, 12. As can 
be seen from an inspection of FIG. 4, the cleats 29 can form a connection 
laterally between the track sections 27A, 27B, and 28A, 28B. A drive shaft 
23 is mounted on one end of each one of the pontoons 11, 12 and is 
connected to each endless drive track 27, 28 for driving the track 27, 28 
with the plurality of sprockets 25A-25D. 
Each shaft 34 is made sufficiently short so that bogie wheels 30 can be 
positioned inboard of the sides 11A, 11B and 12A, 12B of pontoons 11, 12 
(see FIG. 4). By positioning the bogie wheels 30 inboard of pontoon sides 
11A, 12A and 11B, 12B, a pair of lugs 32, 33 can be positioned 
respectively on each side of each bogie wheel 30. Thus the lugs 32, 33 
form a track retention system with bogie wheels 30 for each pontoon 11, 12 
and its associated track 27, 28. The lugs 32, 33 are positioned on both 
sides of each series of bogie wheels 30, the lugs also defining a load 
transfer between the sprockets 25A-D and the tracks 27, 28. Each lug 32, 
33 includes preferably a solid block of material such as a high density 
plastic such as urethane, for example, and each lug 32, 33 includes an 
arcuate section 32A, 33A which is generally semicircular in cross section 
and is shaped to register with and intermesh with each sprocket 25A-25D 
(see FIG. 3), and a guide portion 32B, 33B which extends inwardly a 
distance beyond the curved portion 32A as shown in FIGS. 1, 3, and 4. The 
top 11C, 12C of each pontoon is provided with a pair of longitudinally 
extending rails 35, 36. Lugs 32, 33 register upon the rails 35, 36 as 
shown in FIG. 6. Each rail includes a longitudinally extending indented 
portion 37 along its inside and outside edges as shown in FIG. 6, the 
indented portion registering with the guide 32B, 33B portions of lugs 32, 
33. Rails 35, 36 can be manufactured of a plastic material having a low 
coefficient of friction. Alternately a series of idler support wheels can 
be used in place of rails 35, 36. 
In the embodiment of FIG. 3A, the drive shafts 23 is connected to sprocket 
assembly 50 which includes a pair of sprocket members 50A, having guide 
wheel 52 therebetween. The assembly 50 can be bolted together for example 
using a plurality of bolted connection 54. 
In view of the numerous modifications which could be made to the preferred 
embodiments disclosed herein without departing from the scope or spirit of 
the present invention, the details herein are to be interpreted as 
illustrative and not in a limiting sense.