Toro Reelmaster 3100-D Service Manual page 98

Lower Cutting Units
Hydraulic System: Hydraulic Flow Diagrams
The gear pump (P2) is directly coupled to the hydrostat through gear pump
(P1). It supplies hydraulic pressure (charge pressure) for raising and lowering
the cutting units, operating the sidewinder unit, and replenishing the closed
loop traction circuit (charge pressure). The pump takes its suction directly from
the hydraulic tank.
During conditions of not lifting or lowering cutting units, flow from the gear
pump (P2) is by−passed through the power steering valve, 2−spool valve, and
hydraulic manifold directly to the hydrostat and the charge relief valve. Flow then
returns to the hydraulic tank.
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.
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 action 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 cylinder movement. The
cylinder position is locked in place since there is no complete circuit of flow
to and from the lift cylinders.
Page 5–22 Reelmaster ® 3100-D/3105-D
20252SL Rev A