Service Manual

Reelmaster 3100−D
Page 4 − 17
Lift Circuit (Down)
Lower Cutting Units
Circuit operation for lowering the cutting units is similar
to raising them. However, pressure is relieved from the
lift cylinders, and this action allows them to lower.
During conditions of not lifting or lowering cutting units,
flow from the gear pump is by−passed through the pow-
er steering valve, 2−spool valve, and hydraulic manifold
directly to the hydrostat and the charge relief valve. Flow
then returns to the hydraulic tank.
When the cutting units are to be lowered, the 2−spool
valve is positioned by moving the cutting unit shift lever
to LOWER. Pressure from gear pump (P2) is used to
shift the pilot valve in the 2−spool valve. This shifting of
the pilot valve allows hydraulic pressure to relieve from
the cap end of the lift cylinders. Flow from the cap end
of the lift cylinders causes the cutting units to lower. At
the same time, the fluid relieved from the cap end of the
lift cylinders goes into the rod end of the cylinders and
back through the hydraulic manifold to the hydrostat.
When the cutting unit shift lever is released, spring ac-
tion returns and detents the valve into the float position
while by−passing flow back to the hydrostat. The pilot
valve then shifts to its original position and stops lift cyl-
inder movement. The cylinder position is locked in place
since there is no complete circuit of flow to and from the
lift cylinders.
Hydraulic
System
Hydraulic System