CLAAS ACADEMY LEXION II Steering hydraulics Function of steering operation By turning the steering wheel in one direction or the other, causes the inner spool (609) to turn up to 8° to the outer spool (609). This causes the return from the pump (218) to tank to be closed and the connection to the measuring unit (229) is opened. The oil flow rate is dependent on the rotation, amount and speed of the rotor (229) and the rotary valve (609) to the ram of ram ring flange of the steering rams (323). The displacing flange area of the ram (323) is thus connected via rotary valve (609) to the return flow to the tank.
As soon as the steering wheel is released, the springs return the inner and outer spool (609) back to the neutral position. As soon as they are returned to the neutral position, then either end on the ram is locked and the connection between pump (218) and tank re-instated. Function of the emergency steering When the steering pump (218) fails to deliver oil to the steering system, the one way valve (742) closes, ensuring that no oil can flow out from the system. Operating the steering wheel in one direction or the other will turn the inner and outer spool (609) in an opposite direction.
Oil is then pumped by the rotor (229) using muscel power from one side of the steering ram (323) to the other, via the one way valve (728). Machines that are only equipped with one ram (323), require the reservoir as one side of the ram has a different surface area to the other. 02/2001 2-11