Why do you need to change the hydrostatic transmission fluid? If you have a lawn mower, I advise you to learn when to change its hydrostatic transmission fluid.
I don’t wait before my lawn mower develops fault before I remember to carry out maintenance, especially on its hydrostatic transmission.
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Hydrostatic Transmission
The hydrostatic transmission in your lawn tractor requires servicing that includes draining the old hydrostatic oil, changing the filter, and adding new hydrostatic oil.
Hydrostatic transmissions consist of a hydraulic pump and motor that is belt-driven from the lawn tractor engine to propel the lawn tractor forward and backward by a foot-controlled pedal or hand lever.
The hydrostatic transmission oil fill reservoir is generally located under the lawn tractor seat, but some model lawn tractors have two transmission oil fill reservoirs.
How to change the hydrostatic transmission fluid
Park the lawn tractor on a flat, level working surface and allow the engine and transmission to fully cool before filling the transmission. Set the lawn tractor park brake to prevent the lawn tractor from shifting or rolling while working.
Slide an oil-catch drain pan directly under the hydrostatic transmission oil drain plug to catch the old transmission oil. The transmission oil drain plug is generally located on the side of the transmission towards the bottom.
Some lawn tractor type and model hydrostatic transmissions may have one or more transmission oil drain plugs, one for the hydrostatic transmission side and the other for the differential gear side.
Clean dirt and debris from around the hydrostatic transmission oil reservoir cap with a clean shop towel to prevent the hydrostatic transmission and the transmission oiling system from being contaminated.
Some hydrostatic transmissions have more than one transmission oil reservoir located under the lawn tractor seat: one that fills the hydrostatic transmission side, and the other fills the differential gear side. An internal cavity connects both the differential and hydrostatic transmission.
Loosen the hydrostatic transmission oil reservoir cap by hand to allow the transmission oil to drain. A loose cap allows air to enter the oiling system, eliminating air vacuum and providing better oil flow drainage.
Unscrew the hydrostatic transmission oil drain plugs with a socket wrench, and allow the transmission oil to fully drain.
Screw the transmission oil drain plugs into the transmission. Torque the transmission oil drain plugs with a socket and torque wrench. Refer to your lawn tractor manufacturer’s owner operator’s manual for specific transmission oil drain plug torque specifications.
Slide the transmission oil drain pan directly under the hydrostatic transmission oil filter. Some make and model hydrostatic transmissions are equipped with a transmission oil filter to clean the transmission oil, lengthening the transmission oil life.
Unscrew the hydrostatic transmission oil filter from the transmission oil filter housing with an oil filter wrench. Slide the oil filter wrench onto the oil filter. Turn the oil filter counterclockwise to unscrew the transmission oil filter from the oil filter housing.
Apply a light coat of clean hydrostatic transmission oil to the new transmission oil filter seal with your finger. Screw the new oil filter onto the oil filter housing by hand. Finish tightening the transmission oil filter with the oil filter wrench. Slide the transmission oil drain pan from under the transmission oil filter.
Fill the hydrostatic transmission oil filter reservoirs with new hydrostatic transmission oil. Pour the transmission oil into the reservoirs by hand. Fill the oil reservoir to the full line embossed on the reservoir tank’s side.
Screw the transmission oil reservoir fill caps onto the reservoir, and tighten the caps by hand. Start the lawn tractor engine. Check for transmission oil leaks around the transmission oil drain plugs and transmission filter housing. Drive the tractor forward and reverse several times to check for proper transmission operation.
Park the lawn tractor on a flat, level surface. Stop the lawn tractor engine and check the hydrostatic transmission oil level. Add additional transmission oil if necessary, bringing the oil level up to the full line on the transmission oil reservoir.
Things You Will Need To Change Transmission Oil
- Oil catch drain pan
- Clean shop towel
- Socket wrench
- Socket
- Torque wrench
- Oil filter wrench
- Hydrostatic transmission oil
- Hydrostatic transmission oil filter
Tips for Transmission Oil Change
- Always check the hydrostatic transmission oil level when the engine and transmission are cool. Hydrostatic transmission oil expands with heat and can give a false reading when hot.
- Transmission fluid deteriorates over time. To prevent damage to the transmission, you should change it frequently enough. How often you change your transmission fluid depends on how heavy the transmission is.
- If you mainly drive in the city, you frequently stop and go. This will increase the transmission’s operating temperature, which means the pressure is higher on the transmission fluid.
- Other circumstances such as carrying a heavy load in cars with high torque or towing a trailer will also increase this pressure. This heavy use will accelerate the deterioration of the transmission fluid.
A change is advised every 90.000 km, but this differs per car, so always check your owners´ manual to see what range is advised.
Meanwhile, hydrostatic transmissions are less efficient than gear transmissions when translating engine horsepower into power take-off or PTO. Therefore, people who use PTO-driven implements must double-check that the PTO horsepower of their machine with the hydrostatic transmission is strong enough to handle the tasks.
Failure of any mechanical component, a broken hose, or clogged filter will cause tractor hydrostatic transmission problems. But the most common issue will be the oil itself. In the transmission section of your operator’s manual, you’ll find a section that covers oil viscosity
FAQs
When should you change the hydrostatic fluid?
After the second hydrostatic fluid change, you should replace the fluid every 100 hours of use
Do you need to change the hydrostatic transmission fluid?
Replacing hydrostatic fluid is normally unnecessary unless the drive system needs some other internal service or repair.
Do hydrostatic transmissions need fluid?
The hydrostatic transmission in your lawn tractor requires servicing that includes draining the old hydrostatic oil, changing the filter, and adding new hydrostatic oil.
