Earth working – With seat or attendant's station
Reexamination Certificate
1999-07-12
2001-02-06
Batson, Victor (Department: 3671)
Earth working
With seat or attendant's station
C172S776000, C296S190050
Reexamination Certificate
active
06182771
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to a tractor with a ground-working implement such as a rotary plow drivably and vertically movably coupled thereto.
2. Description of the Related Art
A conventional tractor of the type noted above is disclosed in Japanese Utility Model Publication Kokai No. 60-22103, for example. According to this publication, control valves for controlling hydraulic cylinders are mounted on the upper surface of a lid plate closing an opening formed in the upper surface of a transmission case.
In such a case, a plurality of control valves are arranged on the upper surface of the lid plate of the transmission case. The conventional construction noted above requires hydraulic piping to provide communication among the control valves. Otherwise, the control valves must be directly interconnected to communicate with one another.
Thus, where the control valves are interconnected through hydraulic piping, the conventional construction noted above requires an operation to install the control valves on the lid plate, and an operation to connect the hydraulic piping to the control valves. Where the control valves are interconnected directly, the conventional construction requires an operation to connect the control valves to one another, besides the operation to install the control valves on the lid plate. All these operations render a poor work efficiency of assembling the control valves.
Moreover, when removing one control valve from the lid plate to carry out maintenance, a troublesome operation is required, such as disassembling the hydraulic piping, or disconnecting the control valve from the other control valves. The conventional construction also lacks in facility of maintenance.
SUMMARY OF THE INVENTION
The object of this invention is to improve the efficiency of assembly and maintenance.
A tractor according to this invention comprises lift arms vertically pivotable relative to a transmission case disposed in a rear position of a vehicle body, about an axis extending transversely of the vehicle body, a lid plate for closing an upper opening formed in the transmission case, and a plurality of control valves arranged on an upper surface of the lid plate for controlling hydraulic cylinders that swing the lift arms, the lid plate defining oil lines for intercommunicating the control valves.
In the above construction, the lid plate supporting the control valves defines oil lines for intercommunicating the control valves. Thus, only by placing the control valves in predetermined positions of the lid plate, installation of the control valves and connection among the control valves are completed. As a result, assembly and maintenance of the control valves are carried out with excellent work efficiency.
In an embodiment of this invention, hydraulic cylinders for swinging the lift arms, preferably, are arranged rearwardly and outwardly of the transmission case. This construction has an advantage, for example, over the case of incorporating the hydraulic cylinders in upper positions of the transmission case, of allowing a seat to be mounted at a reduced height above the transmission case.
In the embodiment of this invention, the control valves for controlling the hydraulic cylinders, preferably, are disposed forwardly of a control valve for controlling a different hydraulic device. With this construction, a distance is secured between the hydraulic cylinders and the control valves for controlling the hydraulic cylinders, by arranging the control valves for controlling the hydraulic cylinders forwardly of the control valve for controlling the different hydraulic device. Compared with the case of arranging the control valves in the opposite fore and aft relationship, hydraulic hoses having increased lengths may be used to connect the hydraulic cylinders to the control valves for controlling the hydraulic cylinders. Consequently, the hydraulic hoses may be handled with ease, and connection between the hydraulic cylinders and the control valves for controlling the hydraulic cylinders may be performed with excellent work efficiency.
Preferably, a seat supporting floor sheet is disposed above the transmission case, which sheet defines a maintenance opening in a position thereof opposed to an area of installation of the control valves for controlling the hydraulic cylinders and the control valve for controlling the different hydraulic device, the maintenance opening being closed by a detachable lid. This construction allows an operation to maintain the control valves to be carried out through the maintenance opening. This maintenance operation is possible although an area over the control valves is covered by the floor sheet.
In the embodiment of this invention, the control valves for controlling the hydraulic cylinders and the control valve for controlling the different hydraulic device, preferably, are secured to the lid plate by tightening bolts from above. This construction facilitates maintenance, including detachment and attachment, of the control valves performed through the opening formed in the floor sheet.
Where a seat is mounted on the lid of the floor sheet, the seat may be removed along with the lid. Thus, the seat does not obstruct an operation to maintain the control valves carried out with the lid removed to expose the opening.
In the embodiment of this invention, the maintenance opening is formed to envelope the area of control valve installation in plan view. This construction allows tools and the like easy access to the control valves through the opening, thereby to facilitate maintenance, including detachment and attachment, of the control valves.
The tractor may further comprise a bracket for pivotably supporting the lift arms, the bracket being attached along with the lid plate to a main body of the transmission case by common bolts. This construction allows the bracket and lid plate to be attached with excellent work efficiency, and realizes a mounting structure serving a plurality of purposes.
In the embodiment of this invention, the bracket for pivotably supporting the lift arms is formed integral with the lid plate. In this way, the two components may be integrated into a single unit.
This integrating feature not only realizes a simplified construction but improves assembling efficiency.
REFERENCES:
patent: 3922932 (1975-12-01), Sugiyama et al.
patent: 4315548 (1982-02-01), Nakamura et al.
patent: 4570425 (1986-02-01), Carr
patent: 5823285 (1998-10-01), Tsuchihashi et al.
patent: 6053257 (2000-04-01), Sugiyama et al.
patent: 60-22103 (1985-02-01), None
Hattori Akio
Nakamura Kentaro
Batson Victor
Kubota Corporation
Webb Ziesenheim & Logsdon Orkin & Hanson, P.C.
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