MacDon M155 Operators Manual - Manual (Page 384)

MAINTENANCE AND SERVICING
Traction Drive Hydraulics
Transmission Oil Pressure
The windrower transmission consists of two variable displacement axial piston hydraulic pumps, one for each
drive wheel.
The pumps are driven through a gearbox from the engine. Each pump requires charge flow to make up for internal
leakage, maintain positive pressure in the main circuit, provide flow for cooling, and replace any leakage losses from
external valving or auxiliary systems.
The charge pressure is monitored, and if it drops below 250 psi (1725 kPa), the cab display module (CDM) sounds
a tone, and displays a flashing warning. Refer to
3.18.4 Cab Display Module (CDM) Warning/Alarms, page 82 .
IMPORTANT:
Rated charge pressure MUST be maintained under all conditions of operation to prevent damage
to the transmission.
If the TRANS OIL PRESSURE warning is displayed, shut down engine, and proceed as follows:
1. Check the hydraulic fluid level in the tank. Refer to Checking and Filling Hydraulic Oil, page 360 .
2. Check the hoses and lines for leakage.
3. Check the charge pressure relief valve. Refer to Checking Charge Pump Pressure, page 368 .
4. If charge pressure still cannot be maintained, do NOT operate the windrower. Contact your MacDon Dealer.
Checking Charge Pump Pressure
DANGER
Stop engine and remove key from ignition before leaving operator's seat for any reason. A child or even a
pet could engage an idling machine.
Incorrect charge pressure settings may result in the inability to build required system pressure and/or inadequate
loop flushing flows.
Correct charge pressure MUST be maintained under all conditions to maintain pump control performance and to
operate the brake release.
Check charge pump pressure as follows:
1. Open hood fully. Refer to 5.4.3 Opening Hood (Highest
Position), page 267 .
2. Attach a 0–600 psi (4000 kPa) pressure gauge to a
hose that is long enough to allow pressure gauge to be
read from the operator’s seat.
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