Excavating – Scoop or excavating and transporting container
Reexamination Certificate
1998-12-15
2001-10-30
Pezzuto, Robert E. (Department: 3671)
Excavating
Scoop or excavating and transporting container
C037S466000
Reexamination Certificate
active
06308441
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to a material handling vehicle such as an excavator and, more particularly, to a material handling vehicle having a lower truck chassis which includes a truck cab and an upper structure which includes an upper cab and a material handling implement, such vehicle having a single engine on the lower chassis which provides power for operation under the control of an operator in either cab.
2. Description of the Prior Art
Frequently, a heavy-duty material handling vehicle such as a crane or excavator includes a lower or truck chassis on which is horizontally pivotally mounted an upper structure that supports the desired material handling implement. The truck chassis is capable of being driven over the road or highway under the control of an operator in the main truck cab. An upper structure is mounted on the truck chassis by a swing bearing through which a center pin extends for relative movement with respect to the truck chassis. An upper structure operator's cab is provided on the upper structure to move with a material handling boom and implement. During operation at a construction site, an operator in the upper structure operator cab can control movement of the truck chassis and also the material handling mechanism.
Previously, in order to provide for remote operation from the upper structure cab of both the manipulations of the material handling mechanism as well as the movement of the entire vehicle, two separate engines were required. One engine was mounted on the truck chassis and controls the highway operation of the vehicle. A separate engine was mounted on the upper structure and provided motive power both to the material handling mechanism as well as powering, through a hydraulic pump and motor, the motion of the truck chassis. U.S. Pat. No. 3,599,814 teaches a remote drive mechanism for powering the drive wheels from an auxiliary engine mounted on the upper structure. U.S. Pat. No. 4,318,451 also teaches a material handling vehicle having a power supply on the upper structure which through a hydraulic motor drives the vehicle at the job site.
As is well known in the art, the previously unavoidable requirement of two separate engines, one on the truck chassis and one on the upper structure, was fraught with a host of disadvantages. For example, with the prior art construction requiring two separate engines the additional weight and cost of the auxiliary engine itself as well as duplicate fuel tanks, radiators, battery and charging systems, air compressors and dryers, power steering pumps, air cleaners and exhaust systems, controls, shroudings and mountings, noise barriers, engine gauges, etc. are incurred. In addition, duplicate maintenance functions are involved in a two-engine vehicle and operating costs are necessarily increased.
In an effort to overcome the problems associated with two engine excavators, the single engine excavator disclosed in U.S. Pat. No. 4,705,450 was developed. That patent discloses a drive train for an excavator having an engine mounted on a lower chassis which is coupled to an automatic powershift transmission. The disclosures of U.S. Pat. No. 4,705,450 are hereby incorporated herein by reference.
Despite the many advantages of the excavator disclosed in U.S. Pat. No. 4,705,405, there are features associated with the powershift transmission which could withstand improvement. For example, the powershift transmission and its required support system is relatively complicated and costly. As such, initial, maintenance, and repair/replacement costs for powershift transmissions are increased. Also, such transmissions consume energy which translates into lower excavator highway transport speeds and increased fuel usage.
The subject invention is directed toward an improved material handling apparatus which overcomes, among others, the above-discussed problems with material handling vehicles and which is effective to sufficiently power all customary remotely controlled functions of a material handling apparatus while requiring only one engine driving into a manual transmission.
SUMMARY OF THE INVENTION
In accordance with the present invention, there is provided an improved material handling vehicle which includes a lower chassis having a truck cab and a relatively movable upper structure pivotally mounted on the lower chassis and having an operator's cab thereon. However, the present apparatus requires only a single, lower chassis mounted engine for powering both movement of the vehicle to the job site under the control of an operator in the truck cab and for both material handling implement operation and vehicle movement around the job site controlled by an operator situated in the upper cab. When driving to the job site, the engine powers the lower chassis drive wheels through a manual transmission in a conventional manner. When remote chassis or material handling implement operation are to be directed from the upper cab, the engine, through a power takeoff on the front countershaft of the transmission, drives a hydraulic pump. The engine does not then directly deliver power to the driven chassis wheels in a conventional manner. The pressurized hydraulic fluid from the hydraulic pump is fed through a propel control valve to a remote drive hydraulic motor which produces rotational force that is driven into the transmission through a second power input thereto. The transmission, through the second power input, drives the driven wheels of the vehicle. Direction of movement is selected by driving the hydraulic motor in the desired direction while two remotely controlled transmission gear ranges are available. In addition, the hydraulic pump provides pressurized hydraulic fluid through control valves to power the various manipulations of the material handling system.
The single engine thus supplies both conventional over-the-road power for the truck chassis and also power for the hydraulic pump and, hence, to the remote drive motor for onsite remote drive or to power the various implement operations. The drive arrangement allows either rear wheel drive or four-wheel drive of the carrier. For a rear wheel drive configuration, the engine directly drives the manual transmission directly connected, by means of a drive shaft, to a rear drive axle and, hence, the rear wheels. In a four-wheel drive configuration, the drive shaft drives a specific rear differential which drives the rear drive axle and its rear wheels by means of a rear drive shaft. The rear differential has a powershaft which drives another drive shaft coupled to a front drive axle and the front wheels.
To operate the material handling apparatus, the engine must not be running when shifting into the remote operating mode from the truck cab. Shifting to remote operation engages the hydraulic pump through an air shift cylinder in operative connection with the front power takeoff on the transmission. The engine is then started from the upper cab and the operator can operate the unit from the upper cab as he would a standard telescoping boom hydraulic material handler, such as an excavator. Control of the engine speed from the upper structure is accomplished through a remote throttle and an engine monitor.
The hydraulic pump pumps hydraulic fluid through a propel control valve, which directs the fluid either through the center pin to the upper structure implements or to the hydraulic motors and then through the center pin to the upper structure hydraulic reservoir. On the upper structure, the supply of pressurized hydraulic fluid is directed by control valves to power the implement hydraulic circuits independently and/or simultaneously. If the operator engages the remote travel control, the flow to the upper structure is reduced but operation and continuance of all implement motions is still possible.
Accordingly, the present invention provides solutions to the aforementioned problems relating to a dual-engined material handling vehicle. As the single engine arrangement provided is sufficient to both routinely dri
Kirkpatrick & Lockhart LLP
Petravick Meredith C.
Pezzuto Robert E.
The Gradall Company
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