MTD 2010 Shop Manual page 17

For Parts Call 606-678-9623 or 606-561-4983
Pressurized line to
the control valve
Figure 3.4
Check valve
Figure 3.5
Pump
718-04127
718-04729
718-04128
Pump
Suction hose
By-pass valve
Pump By-pass Settings
Tonnage
21,25 and 27
27 ton HP pump
33
www.mymowerparts.com
The pump draws fluid from the tank, and forces it under
pressure to the control valve. See Figure 3.4.
• The pump is capable of producing 3,400 PSI (234
bar) at a pump speed of 3,500 RPM.
• The pump is a two-stage pump.
• There is no relief valve in the pump.
• There is unloading or by-pass valve in the volume
circuit.
• The pump is direct-driven from the engine.
• The pump delivers pressurized hydraulic fluid to
the control valve.
Two-stage pumps operate in a volume and a pressure
mode.
In the volume mode both stages are pumping fluid to
the control valve. The volume mode is used to rapidly
move the wedge down the beam.
NOTE: The pressure stage flow is at a much lower GPM
rating than the volume stage, but the pressure is
much higher.
In the pressure mode, the pressure of the fluid from the
pressure stage closes the check valve. The fluid coming
out of the volume stage can not open the check valve and
is diverted to the by-pass valve which will dump the fluid to
the intake side of the pump.
The pressure mode is used to drive the wedge through
the wood that is being split.
By-pass Pressure
+ 100 PSI
500 (34 bar)
1000 (69 bar)
700 (48 bar)
Hydrualic Diagnosis
13