Massey Ferguson hydraulic system MK2
The MK2 hydraulic system was fitted to the MF series 100 tractors, 135, 165, 175, 178, 188 etc.
Because of the inherent simplicity of the system the most common hydraulic repairs done in our workshop are Massey's.
However if a tractor operator understands the system these repairs will be minimised.
First have a basic understanding of how the system works.
1 Relief valve
2 Hydraulic pump
3 Ram cylinder
6 Lift cover
Note : The relief valve (1) during the course of repairs will have been removed & replaced with a compact valve which screws into the pump body.
This is a result of spares not being available for the older factory fitted type. Consequently the response control lever on the dipstick housing will no longer function. Response control is to regulate the speed at which the lift arms drop.
When the tractors engine is running the hydraulic pump operates continuosly getting its drive from the transmission PTO output shaft. Four pistons moving back & forth suck oil in through the chambers and push it out through the same chamber outlet valves. The oil flows up through the standpipe between the pump & lift cover. When oil enters the ram cylinder it forces the piston forward and the arms are raised. When the operator places the lever in the down position the lift covers mechanism closes the pumps control valve and the pumps pressure is dumped back into the diff housing. The oil in the ram cylinder returns through the same standpipe & dumps.
The hydraulic system is influenced by the mechanics of the lift cover. The pump is just that. It either pumps oil or dumps oil or both through the control valve.
The hydraulic lift cover mechanism is influenced by the operator using the draft & position control levers, an implements pulling or pushing force on the toggle spring & the upward or downward movement of the lift cover arms.