Land vehicles – Wheeled – Articulated vehicle
Reexamination Certificate
1998-10-08
2001-09-04
DePumpo, Daniel G. (Department: 3611)
Land vehicles
Wheeled
Articulated vehicle
C091S032000, C091S526000, C172S439000, C172S450000
Reexamination Certificate
active
06283488
ABSTRACT:
CROSS-REFERENCE TO RELATED APPLICATION
This application is based upon and claims priority to German Patent Application 197 44 327.3 filed Oct. 8, 1997.
BACKGROUND OF THE INVENTION
The invention relates to a device for stabilizing the two lower steering arms of a tractor. The device is actuable by a hydraulic power lift. One side strut is coupled per lower steering arm. The two steering arms are actuable by a hydraulic power lift. A switching assembly ensures that the two hydraulic cylinders of the side struts can be connected to the hydraulic power lift via a line. A connection containing means jointly disconnects the two hydraulic cylinders from the power lift. Control means establishes a connection at the point when a settable pivot position of the lower steering arms has been reached.
DE 195 37 555 A1 describes a hydraulic cylinder of the side struts pressurized in parallel with the hydraulic power lift. The hydraulic power lift adjusts the lower steering arms. This means that the lower steering arms are centered centrally as a function of the lifting force and the position. The lower steering arms are stabilized only when they are in the process of being lifted. The position switch ensures that, during the lowering process, the hydraulic cylinders of the side struts, together with the hydraulic power lift, are connected to the return flow means. In consequence, when work is carried out on a slope, the downhill forces result in the attached implement being positioned at an angle.
SUMMARY OF THE INVENTION
It is an object of the invention to develop further a device of this species which, independently of the movement of the hydraulic lift, in the sense of carrying out a lifting or lowering movement, enables the tractor operative to select a central or centered position relative to the longitudinal axis of the tractor.
In accordance with the invention, a pre-selection switch and a control valve are arranged, one behind the other, in the connection between the power lift and the two hydraulic cylinders of the side struts. The power lift is loadable by a first pressure source. The pre-selection switch additionally includes a connection for a separate power source. The control valve has at least two ports which are alternatively connectable to the two hydraulic cylinders. One of the ports is connectable to the pre-selection valve. The other of the ports is connectable to the return flow means. A separate pressure source is coupled with the pre-selection switch.
An advantage of this embodiment is that the pre-selection switch can be used either to switch the side struts or hydraulic cylinders of the side struts, in respect of power, in parallel with the pressure agent supply for the hydraulic power lift. Further, the cylinders can be supplied by an independent pressure source. The control valve is used to connect the hydraulic cylinders to the pressure source or to the return flow means.
To ensure that it is possible for the two hydraulic cylinders to be disconnected jointly from the pressure supply and from the return flow means, two embodiments are provided. According to the first embodiment, the control valve has a switching position where the two hydraulic cylinders are disconnected both from the pre-selection switch and from the return flow means. Here, a main switch is incorporated into the control line of a settable position switch for the lower steering arms to actuate the control valve. Actuation is influenced by the position switch. If the controlling power circuit of the position switch is interrupted, the control valve is actuated to assume the shut-off position.
In a further solution, a switchable shut-off valve or a variable flow control valve is incorporated into the connection between the control valve and the hydraulic cylinder. Using a variable flow control valve is additionally advantageous. Here, it is possible to set the degree of damping in respect of applying pressure to the hydraulic cylinders of the side struts. A further advantage exists in that, when lowering the lower steering arms, the reduction in pressure in the hydraulic cylinders also takes place in a dampened way. Thus, the centered position is maintained during the lowering process over a larger stroke. Furthermore, it is possible to shut off the variable flow control valve completely.
From the following detailed description, taken in conjunction with the drawings and subjoined claims, other objects and advantages of the present invention will become apparent to those skilled in the art.
REFERENCES:
patent: 2771306 (1956-11-01), Ash
patent: 3478647 (1969-11-01), Gerber et al.
patent: 3512453 (1970-05-01), Balzer
patent: 3635020 (1972-01-01), Mahlmann
patent: 3705631 (1972-12-01), Seaberg
patent: 3877345 (1975-04-01), Ohms et al.
patent: 4330008 (1982-05-01), Skelly
patent: 4341149 (1982-07-01), Dezelan
patent: 4454715 (1984-06-01), Muller et al.
patent: 4523886 (1985-06-01), Reeves
patent: 4736673 (1988-04-01), Harada et al.
patent: 4902030 (1990-02-01), Andre
patent: 6035943 (2000-03-01), Gerein et al.
patent: DE 31 13 915 A1 (1982-10-01), None
patent: G 85 16 603.0 (1986-04-01), None
patent: DE 35 27 774 A1 (1987-02-01), None
patent: DE 195 37 555 A1 (1997-04-01), None
patent: GB 2238455 A (1991-06-01), None
patent: 3082683 (1991-04-01), None
Adamek Wolfgang
Coenen Herbert
Vollmer Jurgen
DePumpo Daniel G.
GKN Walterscheid GmbH
Harness & Dickey & Pierce P.L.C.
LandOfFree
Device for stabilizing the lower steering arms of a tractor does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Device for stabilizing the lower steering arms of a tractor, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Device for stabilizing the lower steering arms of a tractor will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2510202