Motor vehicles – Special wheel base – Five or more wheels
Reexamination Certificate
1999-09-24
2002-04-16
Vanaman, Frank (Department: 3611)
Motor vehicles
Special wheel base
Five or more wheels
C180S209000
Reexamination Certificate
active
06371227
ABSTRACT:
BACKGROUND OF THE INVENTION
I. Field of the Invention
The present invention is directed generally to controlling auxiliary pusher or trailer load support axles for utility or load hauling vehicles such as dump trucks, over-the-road tractors and trailers, transit concrete mixing trucks or refuse collecting vehicles. The auxiliary pusher or trailer axle systems are used to selectively deploy auxiliary wheels in a ground-engaging, load-supporting position or to retract them to an elevated or stowed position. The systems are normally operated by forces generated by hydraulic cylinders or pneumatic springs and the amount of load support may be varied by varying cylinder pressure. The present invention more particularly relates to the automatic control of the relative amount of shared support, in keeping with the vehicle loading weight so that the axle loading of the vehicle is compensated accordingly to optimize load distribution.
II. Related Art
Transit concrete mixers are typical among those commercial vehicles that are called upon to haul a variety of load weights at different times. Such vehicles further typically include a single set of forward steering wheels and a plurality of rear, load-supporting drive axles carrying dual wheel arrangements, all mounted on an elongated continuous chassis. The chassis length or distance between certain sets of dual wheel arrangements may further be adjustable in some models. For additional support, particularly in transit when loading exceeds a minimum amount, vehicles of the class typically are provided with one or more pivotally mounted, hydraulically or pneumatically operated, auxiliary axles able to operate between a raised or stowed position carried by the truck and in a load-bearing or deployed position wherein the auxiliary axle and its wheels share the load of the truck with the permanent steering and drive wheel system. Auxiliary axles mounted forward of the drive wheels of a vehicle are typically referred to as pusher axles and those mounted aft of the drive wheels are known as trailer or tag axles. Each auxiliary axle system includes two or more wheels and possibly a plurality of dual wheel axles in such systems, the wheels may be connected by one or more through or common shafts or be independently mounted on stub axles.
Not only does an auxiliary pusher or trailer axle system assist in balancing the load carried by the truck adding safety and convenience, it also enables the truck to carry a higher total payload than would otherwise be permitted by adding one or more additional load bearing axles to which a portion of the load may be distributed to meet legal load per-axle limitations. Because the load often varies, with time however, it is often desirable to adjust the pressure in the system deploying the auxiliary axle so that the axle loading and thus the distribution of weight to the various axles of the truck is maintained at an optimum to compensate for the total loading of the vehicle.
Examples of prior auxiliary axle systems utilized with transit concrete mixing vehicles include U.S. Pat. No. 4,195,856 to Larson et al, U.S. Pat. No. 4,705,133 to Christenson et al; U.S. Pat. No. 5,498,021 to Christenson and U.S. Pat. No. 5,549,322 to Hauri. Additional tag axle systems as applied to load hauling vehicles of the refuse collecting class can be found in U.S. Pat. No. 5,090,495 to Christenson; U.S. Pat. No. 5,597,174 to Christenson et al; and U.S. Pat. No. 5,713,42,4, also to Christenson.
While these and similar embodiments have been relatively successful over the years, prior pusher and tag or trailer axles have either had no provision for adjusting the pressure applied to the deployed axle or have had only manually operable systems for adjusting the pressure applied to the axle to adjust road force in response to estimated truck payload weights. Charts for adjusting such systems manually based on estimated data may be provided for drivers to follow. One such chart is shown in Table I below. The ability to adjust the hydraulic or pneumatic pressure utilized to lower and apply force to pusher and trailer axles over a rather wide bed range not only allows a transit mixer, for example, to carry a larger legal load of concrete while complying with the required state highway weight laws, but it also allows the system to properly balance a variety of different sized loads. For example, if a driver hauls a ten-yard load of concrete (generally given as 40,000 pounds) on one load and only five yards (20,000 pounds) on another load, clearly the downward force or load carried by an auxiliary pusher or trailer axle should be readjusted downward (lowered) to maintain proper shared load balance coordination among the axles. Likewise, when the driver gets to the jobsite and the load is discharged, the pressure to the trailer axle should be reduced to a minimum or the axle prestowed by manual adjustment.
Manual systems, however, have drawbacks. In certain cases, if the driver fails to readjust the pressure for individual loads, the mixer truck may not comply with state axle weight limitations and, moreover, if the pressure is not properly reduced, the lift exerted by the pusher or trailer axle may reduce traction in the rear drive wheels of the truck. In addition, the estimated payload weights may not be as close to the actual values as desired.
Of course, the same type of load variation and estimation problems arise with respect to the collection of refuse, with large dump trucks, log-hauling vehicles or in other load hauling situations in which the weight of the payload can vary over a fairly wide range with respect to the use of the vehicle. In view of the present state of the art, there remains a need for an auto-responsive control system to modulate the application of force by auxiliary axle systems by automatically adjusting applied
TABLE I
Tag
Tag
Pusher
Tag
Pusher
Front
Tandem
Yardage
Pressure
Axle
Axle
Weight
Weight
Axle
Axle
GVW
4.00
1,200.00
Tag Down
Pusher Up
5,989.39
0.00
15,513.13
25,188.08
46,690.60
5.00
1,200.00
Tag Down
Pusher Up
5,989.39
0.00
15,822.23
28,878.99
50,690.60
6.00
1,400.00
Tag Down
Pusher Up
6,705.95
0.00
16,544.91
31,439.74
54,690.60
7.00
1,800.00
Tag Down
Pusher Up
8,139.08
0.00
17,681.19
32,870.33
58,690.60
8.00
2,400.00
Tag Down
Pusher Up
10,288.77
0.00
19,231.05
33,170.78
62,690.60
9.00
2,500.00
Tag Down
Pusher Down
10,647.06
5,000.00
17,947.34
33,096.20
66,690.60
10.00
3,100.00
Tag Down
Pusher Down
12,796.75
5,000.00
19,304.82
33,589.03
70,690.60
11.00
3,100.00
Tag Down
Pusher Down
12,796.75
5,000.00
19,036.76
37,857.09
74,690.60
hydraulic or pneumatic pressure applied to the system. This would improve both the versatility and the safety of the vehicles.
Accordingly, it is a primary object of the present invention to provide an automated control system for auxiliary axles that is responsive to changes in vehicle payload weight.
It is a further object of the present invention to provide an automated system for controlling the deployment pressure to auxiliary axles including each pusher or trailer axle of a vehicle based on the then-present measured payload weight.
It is a still further object of the present invention to provide an automated deployment control system for auxiliary axles which further indicates present auxiliary axle state and whether the axle should be deployed or stowed.
Yet another object of the present invention is to provide an automated auxiliary axle deployment pressure control system that utilizes real-time payload weight distribution.
Another object of the present invention is to provide an automated auxiliary axle control system that coordinates real-time, payload weight distribution with data from a permanent stored record of unloaded vehicle parameters to provide desired real-time axle/weight distribution.
Other objects or advantages will become apparent to those skilled in the art upon familiarization with the specification, claims and drawings contained
McNeilus Truck and Manufacturing, Inc.
Nikolai & Mersereau , P.A.
Vanaman Frank
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