New Holland WorkMaster 50 Service Manual page 405

Combined functioning of position and draft control
To utilise the lifting device in this condition it is necessary to observe the following instructions:
• Move the position control lever (1) upwards with respect to the backstop (E) until the maximum working depth has
been attained.
• Determine the desired minimum working depth by operating the draft control lever and raising it from its zero position
so that roller (11), acting on the draft cam (12) will move the distributor shaft (21) into the lifting position (C) and
causing a further upward movement of the lifting arms.
Due to the position previously established by position control lever (1), flywheel (7), roller (4) and position cam (6),
the distributor shaft (21) is prevented from entering the lowering position (S) and therefore the arms cannot sink even
though the traction force acting on the top link point (20) will tend to diminish and putting stress on the tension rod
(18) in the direction of arrow (-) (negative).
This condition will not prevent the rock shaft from operating with the draft control when, in the presence of more
consistent soil, the traction force on the top link (20) will tend to increase, exerting pressure on the tension rod (18) in
the direction of arrow (+) (positive).
Consequently the combined operation of position and draft control will limit variations in height towards the ground,
as happens during the use of the draft control, and at the same time ensuring the maximum possible depth desirable.
Hydraulic systems - Main lift system
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