Amphibious vehicle chassis

Details Amphibious vehicle chassis Amphibious vehicle chassis

2000-08-31

2001-11-13

Sotelo, Jesus D. (Department: 3617)

Marine propulsion

Self-propelled vehicle having land and water propulsion means

C180S009620

Reexamination Certificate

active

06315622

ABSTRACT:

BACKGROUND OF THE INVENTION
The present invention relates generally to a chassis for an amphibious vehicle, and more particularly, to an amphibious vehicle chassis which connects adjacent pontoons so as to more effectively distribute the forces between the chassis and the pontoons thereby alleviating the sheer stress on the fasteners used to attach the pontoons to the chassis and providing added strength to the chassis connections.
Amphibious vehicles were first developed over 50 years ago primarily to support oil and gas exploration operations conducted in marshy or swampy terrain. Such vehicles typically include a pair of pontoons connected to a center platform. The pontoons are usually surrounded by a cleated track system which is capable of engaging ground, water, or swamp land to propel the vehicle. One or more endless chains are preferably driven by a sprocket, or other means, and surround each pontoon. The endless chains support the cleated tracks and are guided along the outer surface of the pontoon by guide channels. The cleated tracks are driven about the periphery of the pontoons in order to provide a thrust to the vehicle. By varying the amount and direction of thrust, or track travel, applied to each pontoon, the vehicle can be advanced, turned, or reversed.
Referring to
FIG. 1
, there is shown a tracked amphibious marsh vehicle
10
. Marsh vehicle
10
includes a pair of pontoons
16
,
18
forming a platform
15
to support a machinery
12
thereon. Machinery
12
can be selected from a wide assortment of heavy equipment but is shown in
FIG. 1
as a boom crane. Pontoons
16
,
18
are preferably constructed from steel or aluminum as rigid hollow structures or enclosures to provide sufficient buoyancy or “flotation” in amphibious environments to stabilize and support machinery
12
even on marshy or swampy terrain. Vehicle
10
also includes a lower drive train
14
with a driven endless track
20
,
22
mounted around each of the pontoons
16
,
18
, respectively. A drive system (not shown) is used to independently rotate endless tracks
20
,
22
about their respective pontoons
16
,
18
. The rotation of endless tracks
20
,
22
is the primary method of positioning and guiding marsh vehicle
10
. By varying the speed and direction of each track
20
,
22
, vehicle
10
is able to advance, change course, or reverse.
Over the years, improvements in the structure and integrity of pontoons allow these vehicles to work in more difficult terrain and operating environments. The pontoons are typically constructed of steel or aluminum alloys, are capable of flotation, and are useful for most situations where an amphibious vehicle is required. The pontoons are primarily for the purpose of supporting the deck or platform upon which the heavy machinery is mounted.
The platform and pontoons are connected and held together by a chassis. A typical chassis, along with the platform, is used to support or mount the heavy equipment, including but not limited to, excavators and personnel platforms. A vulnerable aspect of typical amphibious marsh vehicles is the durability of their chassis. The chassis is located between the pontoons and links the pontoons to the platform.
Referring now to
FIG. 2
, there is shown a typical prior art chassis
30
. Prior art chassis
30
includes a central member
32
connecting two pontoons
34
,
36
on either side thereof through two sets of flange plates
38
,
40
and
42
,
44
with a plurality of threaded fasteners
46
. Central member
32
is constructed as a structural beam
48
with a support plate
50
welded thereupon and flanges
38
,
42
at opposite ends. Pontoons
34
,
36
each are constructed as hollowed steel or aluminum enclosures
52
,
54
and are welded to extension members
56
,
58
. Extension members
56
,
58
are thus welded to flanges
40
,
44
which are in turn flanged up with flanges
38
,
42
and bolted together by fasteners
46
.
When an equipment module is placed on chassis
30
, a normal force of large magnitude is applied to chassis
30
in direction W, generally perpendicular to the ground. Pontoons
34
,
36
provide opposite loads and opposite bending moments P
1
and P
2
, respectively, on the chassis
30
. Ideally, when fasteners
46
are secured, force W and bending moments P
1
, P
2
place the top fasteners, as for example fastener
46
A, in compression and place the bottom fasteners, as for example fastener
46
B, in tension. Under such tensile and compressive conditions, fasteners
46
must be robust.
However, when fasteners
46
are not properly secured or become loosened, shear stresses act generally along shear planes E and F causing adjacent flanges
38
,
40
and
42
,
44
to move in shear. Threaded fasteners, preferably in the form of bolts with corresponding nuts, are generally much stronger in tension and compression than they are in shear. Loosened fasteners
46
in prior art chassis designs can experience severe shear loads and are highly likely to fail in service. Such loosening of fasteners
46
can be the result of vibration or fatigue loading conditions. These loading conditions are highly prevalent in marsh vehicle environments and must be accommodated to prevent failure in service.
Because of the weight of the heavy equipment and the buoyant forces of the pontoons, the chassis undergoes tremendous forces. The vibratory forces and fatigue forces from the operation of the vehicle itself, the movement in the rugged terrain, the forces caused by the operation of the heavy equipment, such as an excavator, and the movement of the pontoons due to their buoyancy, prevent the long term durability of these vehicles.
Recently, demand in the industry is growing for vehicles that can perform even more rugged tasks with even heavier equipment, making larger marsh vehicles with higher load carrying capabilities necessary. Additionally, the terrain, wherein these amphibious vehicles are deployed, continues to get more and more treacherous as locations become more remote. Combined, the increase in size and the difficult terrain, mandates that the structural integrity of the vehicles meets rigorous, exacting standards. The remote locations where such vehicles are deployed also prohibits much routine and preventative maintenance. Therefore, there is a need for vehicles that can carry out operations in more remote locales and which require less maintenance.
The typical chassis is not designed to withstand these rigors and, consequently, tends to fail under such conditions. Particularly, it often occurs that the bolts that hold the vehicle chassis together, become loosened through the vibratory and fatigue loads that the chassis experiences. When chassis bolts become loose, failures in the chassis occur, pontoons become disconnected, requiring expensive and time consuming field repair operations. There is a need among the amphibious vehicle industry for a chassis that reduces or eliminates such failures. With a more robust chassis, larger amphibious vehicles with heavier equipment can be deployed in marshy regions, thus reducing the amount of time and resources required to perform many operations, such as construction or demolition, in rugged terrain and difficult environments.
The present invention overcomes the deficiencies of the prior art.
SUMMARY OF THE INVENTION
In accordance with the present invention, the chassis connects adjacent flotation members. Each of the flotation members have supports projecting therefrom for attaching to the chassis. The chassis includes a pair of beams having opposite ends and sides with an end flange affixed to the ends of the beams. A plate is affixed to one of the opposite sides of the beams and has a length greater than the beams to form extension surfaces. The extension surfaces are connected to the supports on a first plane and the end flanges are connected to the supports on another plane, preferably perpendicular to the first plane and vertical to the ground. The beams are preferably I-beams having a web and opposing extending sides perpendicular to the web. T

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