Ransomes G - PLEX WD series, Service Course Manual

Page: 35 / 181

8C
HYDRAULICS
SECTION 8C. CUTTING CIRCUIT
8C-13
SPECIFICATIONS
Pump: Haldex Barnes Corporation W900 8cc/rev 27.2litres/min @ 3400rpm engine speed.
Cutter Relief valve: 207bar (3000psi)
Motors: Haldex Barnes Corporation W600 12cc Bi-directional 2190rpm @ 3400rpm engine
speed.
CIRCUIT DESCRIPTION
NOTE: All hydraulic pump outputs and pressures are given with the engine at maximum rpm and with the oil at
working temperature.
Oil is drawn into the cutting pump from the hydraulic reservoir ( Shell Tellus 46 grade or equivalent) via the 25
micron suction filter. This oil is displaced by the twin gear pump (8cc) at a rate of 27.2 ltrs/min , at an engine
speed of 3400rpm .
From the pump the oil flows to the “P” port of the Reel drive valve. If reel drive is not enabled the oil passes
through the solenoid valve and returns to the hydraulic reservoir from the “T” port via the cooler.
If the Reel drive is enabled (and the units lowered) the solenoid valve closes and the oil then flows from “M” port
to the Reel motors via the back-lap valve. If forward drive has been selected the oil goes to the front right hand
unit, the front left hand unit and then to the centre unit before returning to the back-lap valve, the cooler and the
reservoir.
Within the Reel drive valve is a variable speed control that comprises a needle valve and a pilot operated spool
valve. Rotating the knurled head of the needle valve allows a proportion of the oil to return to the reservoir
reducing reel speed. The pilot operated pressure compensating spool valve ensures that the selected speed is
maintained regardless of changes in loading.
If one of the Reels becomes jammed by a shoe spike or tee peg then the pressure within the circuit will quickly
increase until it reaches
207bar (3000psi) at which point the relief valve will open allowing oil to return to the
reservoir via the cooler. All reels will then stop rotating.
SAFETY NOTE: To avoid the possibility of serious injury, switch the reel enable switch to off, stop the engine,
remove the key and set the parking brake before attempting to release the obstruction. Never rotate the reel by
pushing with your hands or fingers as energy can be released suddenly resulting in serious injury. Instead use a
suitable length of softwood to ease the obstruction free.