Claas Dominator 140 150 Hydraulic System Steering actuation
When actuating the steering to one or another direction, the Orbitrol rotary disc (609) is rotated by up to 8° relative to the outside spool. During this process, the return line from the steering hydraulics pump (218) to the tank is closed and the connection to the steering hydraulics proportioning pump (229) is released.
Via the steering hydraulics proportioning pump (229) and the Orbitrol rotary disc (609), the volume flow is released as a function of the sense of rotation, path and speed of steering wheel motion to the ram or the ram ring surface of the steering hydraulic cylinder (323). Here, the displacing surface of the steering hydraulic cylinder (323) is connected with the return line to the tank via the Orbitrol rotary disc (609).
As soon as there is no more steering motion, leaf springs bring the outer rotary disc of the Orbitrol rotary disc (609) back to neutral position. Now both sides of the steering cylinder are shut off again and the connection from the steering hydraulics pump (218) to the tank is re-established.
Claas Dominator 140 150 Hydraulic System Emergency steering
When the steering system is not supplied any more by the steering hydraulics pump (218), the steering safety valve (742) closes and thus ensures that no oil will escape from the steering system. When the steering is actuated, the inner and outer disc of the Orbitrol rotary disc (609) are rotated relative to each other. Now the oil can be conveyed from one side of the steering hydraulic cylinder (323) via anticavitation valve (non-return valve) (728) to the other side through human power by the drive of the steering hydraulics proportioning pump (229).
Claas Dominator 140 150 Hydraulic System Pressure relief valve
The pressure relief valve protects the hydraulic system and thus the connected mechanical components from damage by excessive forces. The spring in the pressure relief valve (703) is pre-stressed for a system pressure of 180+10 bar. The pressure setting may be modified by removing or adding shims.
A 0.5 mm shim corresponds to approx. 10 bar
A 1.2 mm shim corresponds to approx. 23 bar
Claas Dominator 140 150 Hydraulic System Function of master valve
The master valve (Y77) blocks the circulating volume flow from P to T of the open hydraulic system when a working hydraulics function has been actuated. Single-acting functions are an exception to this if the consumer is relieved to the tank. In neutral position, the master valve (Y77) is not actuated, making the oil flow back to the tank via the ring channels on the spool (U). Due to the large channel cross-section, the circulation pressure is very low.
When pressure is successfully built up at a consumer, the master valve (Y77) is actuated simultaneously with the directional control valve of the corresponding function. Now spool (U) closes the connection from P to T, and the top ring channel being closed first in order to achieve smooth switching-over. The pressure relief valve (703) opens at a maximum system pressure of 180±10 bar and relieves the pressure to the tank.
Claas Dominator 140 150 Hydraulic System Flow control valve
When the "Lower front attachment ñ fast" function is used, the oil displaced via port A flows to the tank (T) through the restrictor in the control spool of the flow control valve (614). This creates a ram pressure ahead of the control spool, making the latter move against the control spring and restrict the return channel to the tank (T) as a function of the load pressure.
When the load pressure in port A changes, both the volume flow through the restrictor and the load pressure against the control spool change, too, and consequently also the return channel cross-section. This control function keeps the volume flow and therefore the front attachment drop rate constant, independent of the load pressure. The front attachment drop rate is adjusted merely by the pre-stress of the control spring at the handwheel.
Relieve tension of control spring = lower drop rate
Tensioning the control spring = increase drop rate