MTD 18HP service manual F. Hydraulic System, Hydraulic Oil Tank and Filter

Note: If you wish to move the mower by pushing, you must release the dynamic brak- ing. Locate the levers at the rear of the mower. Pull both levers out and lock in position. After pushing the mower to the desired location, return both levers to the operating position (See photo below).

Hydro Release Levers

When the mower is parked with the engine running and the steering levers opened out in the neutral position, the parking brakes should be applied. The parking brakes are drum-type brakes mounted on each traction wheel.They are both engaged by the same operating lever.

1.Adjustments: The parking brake handle is an overcenter lever that should engage with moderate force.

Note: To increase parking brake capacity tighten the brake rods going back to the brake arms equally. Tighten rods one full turn and check parking capacity. Repeat Step.

To adjust either brake individually, disconnect the brake rod from the brake arm by removing the cotter pin from the clevis pin and pulling the clevis pin from the brake clevis. Loosen the hex nut and turn the brake clevis in a clockwise direction one full turn looking down the brake rod. This will tighten the brake about .040 inch. Tighten the hex nut and reassemble the brake clevis to the brake shaft assembly. Normally, both brakes should be adjusted and equal amount.

2.Repair: The mower is equipped with internal wet drum brakes and will not normally require maintenance. If they are not working properly, please contact your service center.

F.Hydraulic System

1.Hoses: Check the hoses from the hydraulic oil tank to the oil filter to the hydraulic lines daily for leaks or abrasion and replace any

damaged hoses. Make certain there are no kinks or twists in any hose.

2.Hydraulic Oil Tank and Filter:

Note: Change the hydraulic oil and the oil filter after the first 50 hours of operation and every 500 hours thereafter.

To drain the hydraulic oil tank, place a 2 gallon drain pan under the drain plug on the bottom of the hydraulic oil tank. Remove the drain plug, drain the tank, then replace the plug. Place the drain pan under the filter and remove the filter by unscrewing in a counterclockwise direction. The filter will be full of oil, so empty it into the drain pan. You don’t have to drain the rest of the hydraulic system. Fill the replacement filter with a good grade of 20W-50 oil and lubricate the sealing surface. Screw the filter onto the filter base until it seats and then another one-half turn to seal.

Note: Always wipe off the hydraulic tank fill

cap and the area around it before removing the cap to prevent dirt from contaminating the oil.

Remove the fill cap and fill the tank with the same 20W-50 oil selected for the filter until the oil level is up to the level of the second hole in the fill tube. Leave this air space for expansion. Start the engine and let it run at idle for about five minutes. Check the filter for leaks. Idling the engine and the pumps in this way will purge any air from the system. Shut off the engine and recheck the oil level in the tank. Top-off if necessary until the oil level is up to the second hole n the fill tube.

Note: After unit is up to operating tempera- ture, turn off engine and re-check hydraulic oil. If oil appears foamy or contains excessive air bubbles, DO NOT OPERATE UNIT. Contact service technician.

3.Hydrostatic Transmissions and motors: The pumps are the hardest-working compo- nents in the hydraulic system. They are in operation all the time the engine is running. Because of extremely close tolerances, wear is an important factor in their life. Contami- nants in the hydraulic oil and cavitation does the greatest harm to the pumps. Cavitation is a blockage in the supply lines that produces a partial vacuum causing violent bubbling in the hydraulic oil in the pump.

Check the two suction hoses (the hoses con- nected to the filter) daily before starting the engine. Look for a flattened condition or any leaks and repair or replace as necessary. A flattened or leakng suction hose will permit

20