DE2551166A1 - HYDRAULIC DEVICE FOR TILTING THE CAB OF A TRUCK - Google Patents

Description

2551166 Dipl.-Ing. A. Spalthoff 43 essen ι, the 1 3rd I *.

Patent attorney Pelmanstrasse 31

Postsdiliessfadi 1533 Telephone (02141) 772008

^{A cycle number} - 22 337

please indicate in the answer

CLAYTON DEWANDRE CO. LTD. Titanic Works, Lincoln England

Hydraulically operating device for tilting the cab of a truck

The invention relates to a hydraulically operating device for tilting the cab of a truck.

The cabs of large trucks built today are often attached so that they can be used to create an access to the internal combustion engine or to other mechanisms can be tilted. Usually for The facilities used for tilting have a double-acting hydraulic piston-cylinder arrangement associated with it as well Actuating and control devices, for example a manually operated piston pump, a control valve, a memory, as well as safety valves, check valves and / or cavitation positioned at suitable points restrictive valves.

In such arrangements for tilting cabs, the piston is usually used to lift the cab to be raised to a point moved beyond equilibrium, so that when the cab falls forward, the

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Piston is pulled to the end of its stroke. For lowering of the cab, pressure is applied to the top of the piston and the cab to a point at which equilibrium prevails, pushed back. The cab can then be lowered into its lowered position in a controlled manner Fall position.

To prevent undesired falling down of the cab from the tilt position are usually used in the piston openings flow restrictors, so that the speed at which the piston can move is limited. It is also possible to use shut-off valves, which completely interrupt the flow of fluid and thus the piston movement and which are forcibly removed from their seats must be removed before the piston can extend or retract. There are also combinations used by flow restrictors and shut-off valves. It has been shown that the check valves, which are usually by actuating the pumped pressure at the opposite ends of the piston have a restrictive effect, when the load extends the piston causing excessive cavitation.

The object on which the invention is based is therefore to create a cab tilting system in which this deficiency has been eliminated.

This task is based on the aforementioned device for tilting the cab of trucks solved by a check valve, in which only the return movement of the piston is controlled, the valve is actuated by the pressure generated in the upper or piston rod end of the cylinder of the unit.

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In a preferred arrangement, flow restrictors or flow restrictors are provided in order to limit the speed of the piston movement.

With reference to the accompanying drawings, the invention is exemplified explained in more detail.

Fig. 1 shows an axial section through a piston-cylinder unit with shut-off valve and flow throttling devices.

FIG. 2 shows a modified one in a view like FIG. 1 Aggregate.

Fig. 3 shows schematically a hydraulic circuit.

The piston-cylinder unit shown in FIGS. 1 and 3 1 conventional design has an eye 2 at its lower end for the articulation to the vehicle frame, while the Piston rod 3 extends up through the free end of the cylinder and for connection to the tilting one Cab is trained. The check valve sits in a shoulder 4 at the lower end of the unit and has a connection 5 on the top and a connection 6 on the bottom for connection to fluid pressure supply lines 7, 8, with which the delivery side of the hand pump of the system is optionally connectable via a control valve, not shown. The upper connection 5 opens via a cross-sectional reduction or throttle point 9 in the outer end of a Ram chamber 1o. A passage 11 in the approach connects this end of the chamber with a sense line 12, which over an upper extension 13 is connected to the cylinder space of the unit above the piston 14. The inner end of the ram chamber 1o is connected to an inlet port 15 which leads into .das lower end of the cylinder of the unit. These Connection is controlled by a spring loaded ball check valve 16. In the chamber 1o is between their

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Ends a plunger 17 arranged on the fluid pressure at outer end of the chamber responds and which, when displaced in this way, the ball valve 16 from its seat moved away via a plunger shaft 17a. The lower connection 6 opens into a passage 18 in the approach. The passage 18 leads into the inner end of the ram chamber 1o between the plunger and the valve-controlled passage to the lower end of the cylinder of the unit.

The pump delivery side is in operation and for raising the cab connected to the lower connection 6, from which the conveyed medium via the passage 18 into the valve housing flows to the space under the plunger 17, whereby the check valve 16 is lifted from its seat, so that the medium can flow into the lower end of the cylinder of the unit and lifts the piston therein, with fluid from the upper end of the cylinder via the line 12, the throttle point 9 in the upper connection 5 and the connected thereto Control valve exits. When the cab passes the point where there is an excess weight, and that's why falls forward, pumping is no longer required. In this case, fluid is then drawn into the lower end of the cylinder pulled from the memory via the assigned control valve? the pressure at the top of the cylinder generated by the Speed throttle 9 is built up, but acts on the plunger and ensures that the check valve 16 is kept away from its seat, eliminating any possibility of cavitation or cavitation in the lower end of the cylinder of the unit is avoided. In this way the cab can travel at a limited speed fall forward.

To return the cab to its lower position, pressurized fluid is supplied from the pump to the upper end of the Cylinder of the unit guided, whereby the piston

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withdraws. At the same time, the check valve 16 is opened, so that fluid from the lower end of the unit can escape. This pressure has to be built up at the upper end of the cylinder of the unit, around the cab to cause a return to the starting position, whereby this pressure should initially be at a level that is enough to move the cabin to the point of equilibrium. Then the weight of the cab acts in Closing direction of the unit, whereby only a pressure is generated that is sufficient to open the shut-off valve.

It has proven to be advantageous to have a damping opening 19 acting in one direction in the underside of the unit provided in order to exclude pressure surges caused by a rapid movement of the piston, which is on The upper end of the unit reduces or loses pressure faster than maintaining such a pressure by the pump can be. In the arrangement shown, there is such a damping opening acting in one direction a small control valve 2o, which is in a cavity in the lower end wall of the cylinder of the unit between the check valve 16 and the inlet port 15 is arranged and two axially spaced openings 21 and 22 for a free flow of fluid flowing into the bottom of the cylinder. The coiled one Control valve is shifted outward when fluid leaks from that end of the cylinder due to the pressure drop, which occurs at the two openings through the flow. This results in the outer opening 21 being covered, so that one obtains a higher flow restriction or a higher throttling of the flow. That way, the in one direction acting speed limiting device or speed throttle or damping opening an equivalent to a throttle parallel to a check valve, as shown schematically in FIG. 3.

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In the modification shown in Fig. 2, the upper pressure fluid connection 5a is made of a modified one Approach 13a at the upper end of the piston-cylinder unit. The connection has a front speed throttle 9a and a sensing line 12a, which thus via a safety throttle 23 and is connected to the upper end of the ram chamber 1o, as explained above. The lower connection consists of the lower approach as described above. The piston-cylinder arrangement works in the same way like the embodiment of FIG. 1.

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Claims (7)

PATENT CLAIMS - 1.) Device for tilting the cab of a truck with a double-acting hydraulic piston-cylinder arrangement and associated actuation and Control devices, characterized by a check valve for controlling the return movement only of the piston (14), the valve being actuatable by the pressure exerted in the upper or piston rod end of the cylinder (1) of the unit is generated. 2. Device according to claim 1, characterized in that that the shut-off valve has a valve housing (4), a pressure fluid inlet connection (5) provided thereon, a passage device for guiding the fluid from the inlet to the lower end of the cylinder (1) of the unit, a spring-loaded check valve (16), which controls the flow of fluid through the passage means, a chamber (1o) in the housing, a plunger (17) in the chamber (1o) and a sensing line (12) which at one end to the space on one side of the plunger (17) and at the other end to the upper end of the cylinder (1) of the unit is connected in such a way that the in the pressure generated by the upper end of the cylinder (1) is transmitted to the chamber (1o) and the plunger (17) shifts so that it comes into engagement with the check valve (16) and this removed from its seat. 3. Apparatus according to claim 2, characterized in that a pressure fluid inlet connection on the valve housing is provided for the upper end of the cylinder (1) of the unit, the connection opening in the plunger chamber (1o) is connected to the sensing line (12) at this end. 609824/0678 4. Apparatus according to claim 2, characterized in that a pressure fluid inlet connection at a separate connection (4) is provided for the upper end of the cylinder (1) of the unit, wherein the extension sits on the cylinder (1) and is connected to the sensing line (12). 5. Apparatus according to claim 3 or 4 _f, characterized in that the inlet connection has a throttle point for the fluid flow or that the inlet connection is assigned such a throttle point. 6. Device according to one of the preceding claims, characterized by an acting in one direction, the speed throttling point at the lower end of the piston-cylinder unit. 7. Device according to one of claims 2 to 5, characterized in that the throttle point for the speed is a control valve (2o) which is seated in a cavity which forms part of the passage device to the lower end of the cylinder (1) of the unit and two axially spaced apart Has openings (21, 22) for a free flow of fluid into the cylinder (1) of the unit, the arrangement being made such that the emerging from the lower end of the cylinder (1) Fluid moves the control valve (2o) so that an opening is covered and the fluid flow is restricted thereby is. 6 0 9 3 2 4 / o 6 7 8