Neutral Stud Adjustment (Pistol Grip). Toro Commercial Walk-Behind Mower, Floating Deck Pistol Grip Hydro, Commercial Walk-Behind Mower, 15HP T-Bar Hydro Drive, Commercial Walk-Behind Mower, 15HP, T-Bar, Hydro Drive, Commercial Walk-Behind Traction Unit, 18HP Pistol-Grip Hydro Drive, Commercial Walk-Behind Mower, 15HP T-Bar Gear Drive, Commercial Walk-Behind Mower, 15HP, T-Bar, Gear Drive, Commercial Walk-Behind Mower, Floating Deck T-Bar Gear, Commercial Walk-Behind Mower, Floating Deck, Split Lever, Hydro Drive, Commercial Walk-Behind Mower, Floating Deck, T-Bar, Gear Drive, Commercial Walk-Behind Traction Unit, 17HP Pistol-Grip Hydro Drive

HYDROSTATIC DRIVE SYSTEM

Bleeding the Hydraulic System

Due to the effects air has on effi ciency in hydrostatic drive applications, it is critical that air is purged from the system.

These purge procedures should be implemented anytime a hydrostatic system has been opened to facilitate maintenance or any additional oil has been added to the system.

Air creates ineffi ciency because it has compression and expansion rates that are higher than that of oil.

Entrained air in the oil may cause the following symptoms:

• Noisy operation

• Lack of power or drive after short-term operation

• High operation temperature and excessive expansion of oil.

Before starting, make sure the reservoir is at the proper oil level. If it is not, fi ll to the vehicle manufacturer’s specifi cations.

The following procedures should be performed with the vehicle drive wheels off the ground, then repeated under normal operating conditions.

WARNING

POTENTIAL FOR SERIOUS INJURY

Certain procedures require the vehicle engine to be operated and the vehicle to be raised off of the ground. To prevent possible injury to the servicing technician and/or bystanders, insure the vehicle is properly secured.

1. Disengage the PTO.

2. Stop the engine and wait for all moving parts to stop before leaving the operating position.

3. Support the rear of the machine on jack stands high enough to raise the drive wheels off the ground.

4. With the bypass valve open and the engine running, slowly move the directional control in both forward and reverse directions (5 to 6 times), as air is purged from the unit, the oil level will drop.

5. With the bypass valve closed and the engine running, slowly move the directional control in both forward and reverse directions (5 to 6 times). Check the oil level, and add oil as required after stopping engine.

6. It may be necessary to repeat Steps 4 and 5 until all the air is completely purged from the system. When the BDP’s move forward and reverse at normal speed purging is complete.

Cleanliness is a key factor in the successful repair of

BDP’s. Thoroughly clean all exposed surfaces prior to any type of maintenance. Cleaning of all parts by using a solvent wash and air drying is usually adequate. As with any precision equipment, all parts must be kept free of foreign material and chemicals. Protect all exposed sealing areas and open cavities from damage and foreign material.

Upon removal, all seals, O-rings, and gaskets should be replaced. During installation, lightly lubricate all seals, O-rings, gaskets with clean petroleum jelly prior to assembly. Also protect the inner diameter of seals by covering the shaft machined features with plastic wrap or equivalent.

6-32 Floating Deck Mid-Size Service Manual