SHAFT 6S3771 - Caterpillar

Introduction
This chapter includes information about auxiliary equipment that your governor may have. Using this section in conjunction with the other chapters in this manual provides instruction and parts for most PSG governors.Auxiliary equipment supported by information in this chapter includes:* Spring-driven, oil-damped ballhead* Torsion spring* Pneumatic speed setting* Electric motor speed setting* Externally adjustable droop* Temperature compensated needle valve* Fuel rod* Internal return spring (vertical or horizontal)Spring-driven, Oil-damped Ballhead
A spring-driven, oil-damped ballhead serves as a filter for torsional vibrations that originate in the drive to the governor. It consists of a ballhead drive cup (driving element) driven from the rotating bushing. The ballhead rests on a thrust bearing carried by the driver. A torsion spring connects the ballhead to the rotating bushing.Torsional vibrations cause relative motion between the drive cup and the ballhead. This movement is inhibited by the action of a volume of oil being forced through a relatively narrow leak path, which provides the damping action.The ballhead fills with oil through a combination of pressure feed and centrifugal action. The fill time varies with dimensional tolerances, governor pressure, and oil viscosity. The ballhead drains down partially on shutdown.Since the oil-feed circuit functions whenever the governor is operating, there is a continuous flow of oil through the ballhead assembly. If the supply of oil is not clean, contaminates will accumulate in the ballhead and the ballhead will eventually assume the characteristics of a solid ballhead. If the governor is subject to excessive dirt accumulation, consider using a separate sump system.Ballhead Check
Check for dirt accumulation by holding the governor drive shaft and turning the ballhead against its internal stop. Repeat in the opposite direction. Travel should be smooth and about 22 degrees is each direction. Replace the ballhead if it does not return promptly to mid position when released.Replace the cover if it is damaged or dished. Damage is normally attributed to rough handling.Check that the flyweights have no flat spots on the toes and that the flyweight bearings are not worn. Also check pivot pins for wear or damage.Parts List for Figure 6-1
Figure 6-1. Exploded View of Oil-damped BallheadTorsion Spring
A torsion spring is provided on PSGs that are equipped with an electric motor for speed setting. The spring is also provided on governors that are not equipped with a speed adjusting shaft, and on governors that are operated below 800 rpm.The spring forces the speed-adjusting lever to maintain contact with either the speed-adjusting screw or the adjusting shaft on the motor.When used with external droop, the spring must mount on the speed-adjusting sleeve, on the side opposite the droop-adjusting shaft.Pneumatic Speed Setting
Remote speed adjustment is provided through a pneumatic speed-setting assembly consisting of a diaphragm, housing, oil reservoir, adjusting screws, and pushrod, extending down through the cover to the floating lever. Air signal pressure to the speed-setting assembly is applied to an oil reservoir to damp out oscillations of air compression. Oil pressure, acting on the diaphragm, is transmitted by the pushrod to the governor floating lever,