DE1076927B - Device for automatic limitation of the load torque with luffing jibs - Google Patents

Description

GERMAN

It is a device for the automatic limitation of the load torque for hydraulically operated ones Luffing booms known, in which a control member serving to shut off the pressure medium supply or return flow is under the influence of the pressure prevailing in the cylinder which actuates the boom and is influenced in the opposite sense by a force that changes with the angle of inclination of the Cylinder axis changes. This control element prevents the boom from overhanging when there is a risk of tipping can be enlarged.

If this device is designed in such a way that it also has the Hoist is stopped in order to prevent that a for a certain radius of the boom If this overhang is taken up to a heavy load, then it must be ensured that the locking effect this device can be canceled in order to be able to set down the raised load again. This could be achieved by the two parts lying in front of and behind the locking device connects the line leading to the hoist drive with a lockable bypass line, as is also necessary for the line leading to the drawing-in unit, to restore the boom move in or be able to lay it out again after the discharge. But then it would be necessary to have two valves to use. If you can connect these to a common actuation means, so is but the effort for this valve arrangement is considerable.

The invention takes a different approach. You can see in the line between the boom lift cylinder and the control member before a switching means that can be operated by hand and the connection between Able to interrupt the cylinder and control member, but at the same time the line part between the Switching means and the control member connects to the drain line.

The switching means, which is designed as a control slide, is preferably provided with an operational shut-off the drainage line serving part and is otherwise designed so that the influencing the control member Hydraulic fluid when the switching means is in the rest position by a limited by the control slide annular part of the cylinder chamber receiving the control slide is guided, the inlet and Derivatives are connected to the cylinder chamber in such a way that counteracting when moving the control slide the action of a spring force closes the pressure medium supply line and then the space behind the control member is connected to the drain line. This becomes the one acting on the control member Liquid pressure is released, and this returns to its original position.

Device for automatic

Limitation of the load torque

with luffing jibs

Applicant:

Demag-Zug GmbH,
ίο Wetter / Ruhr

Walter Ebert, Hagen (Westphalia),
has been named as the inventor

In the drawing is an embodiment of the

ao inventive idea shown.

In the housing designated 5, the control member 6 is displaceable against the action of the spring 7. For this purpose, the line 9 leading to the cylinder of the drawing-in mechanism is connected to the space 15 located behind the control member 6 via the bore 9 α and the cylinder space 20. A second line 21 that can be shut off by the control element leads to the oil motor of the lifting mechanism. If, as the boom swings out, the pressure in the cylinder of the retraction mechanism is greater than the counterpressure of the spring 7 due to an overload, then the pressure fluid moves the control member 6 to the left and blocks the supply of pressure medium to both the retraction mechanism and the lifting mechanism.

The control slide 22, which can be moved in the cylinder chamber 20 and is held in the rest position by a spring 23, serves to render the device ineffective in emergencies, so that the pressure medium from the line 9 through the bore 9 α and the cylinder chamber 20 into the chamber 15 behind the control member 6 can get.

If the protective device is rendered inoperative, then by pressure on the actuating means 22 α bore 9 α closed and then the leading to Abölleitung bore 24 is released, so that the oil contained behind the control element flow out and to return it to its rest position. After releasing the actuating means 22 a , the slide 22 also returns to its starting position under the influence of the spring 23.

Claims (2)

Patent claims: 1. Device for automatic limitation of the load torque with hydraulically operated luffing 909 75 & / 137 boom, in which a control member serving to shut off the pressure medium supply and return flow under the influence of the swiveling movement when the boom is luffed The cylinder is under pressure and is influenced in the opposite sense by a force which changes with the angle of inclination of the cylinder axis, characterized in that when training the device for the simultaneous shut-off of the pressure medium line to the hoist a switching means (22) in the line for the pressure fluid influencing the control element (6) is provided through which this line can be blocked and the line part between the switching means (22) and the control member (6) can be connected to the drain line (24). 2. Device according to claim 1, characterized in that the ausgebil- as a control slide dete and an actuating means (22 a) which penetrates the valve housing and has switching means (22) has one of the operational shut-off of the drain line (24) serving part and the the control member (6) influencing hydraulic fluid when the switching means (22) is in the rest position through the from the control slide bounded annular part of the cylinder space receiving the control slide (20) is performed, the inlet and outlet lines being connected to the cylinder chamber are that when moving the control slide against the action of a spring force (23) the Pressure medium supply line closed and then the space (15) behind the control member (6) with the Drain line (24) is connected. Considered publications:
German patent specification No. 959 129. 1 sheet of drawings © 909 758/137 2.60