HYDRAULIC GOVERNORS
This chapter will deal only with the most common troubles that may be encountered with hydraulic governors. Poor regulation of speed may be due to the faulty adjustment of the governor or to the faulty action of an engine. Or it could be a problem with a synchronizing motor, a voltage regulator, or any piece of equipment that has a direct bearing on the operation of the engine.
Manufacturers stated that 50 percent of all governor troubles are caused by dirty oil. For this reason, you should take every precaution to prevent the oil from becoming contaminated. Most hydraulic governors use the same type of oil that is used in the engine crankcase, provided it is absolutely clean and does not foam. You should change the oil in the governor at regular intervals, depending upon the type of operation. But regardless of the operation or the preventive maintenance schedule, it must be changed at least every 6 months. You must make sure the oil containers used to fill the governors are clean and that only clean, new, or filtered oil is used. You should also check the oil level frequently to make sure the proper level is maintained and the oil does not foam. Foaming oil is usually an indication that water is present in the oil. Water in the oil will cause serious damage to the governor.
When a new or overhauled governor is installed, you should adjust the governor compensating needle valve (even though it has been adjusted previously at the factory or repair facility). This adjustment is made with the governor controlling an engine with a load. If this adjustment is not made, high overspeeds and low underspeeds after load changes will result and the return to normal speeds will be slowed. Follow the procedure listed in the manufacturer’s maintenance manual and the PMS.
When a governor problem is suspected, before performing any maintenance or adjustments, disconnect the governor fuel rod end from the fuel control rack and make sure there is no binding or sticking of the fuel control rack. This procedure will determine if the trouble is actually the governor.
The chart in table 4-1 lists some of the probable causes of problems that are common to most hydraulic governors. This chart is for your general information, and it should not be used as a guide to troubleshoot a governor. You should use the applicable manufacturer’s instruction manual for troubleshooting. The following are the definitions of some terms used in the chart:
HUNTS:Rhythmic variations of speed that can be eliminated by blocking the fuel linkage manually. They will reappear when returned to governor control. SURGES: Rhythmic variations of speed of large magnitude that can be eliminated by blocking the fuel linkage manually. They will not reappear when returned
—Governor Probable Causes and Corrective Actions Chart
to governor control unless the speed adjustment of the load changes.
JIGGLES: High-frequency vibrations of the governor fuel rod end or engine fuel linkage. Do not confuse jiggle with the normal regulating action of the governor.
When normal governor adjustments do not give the desired response, the hydraulic governor should be removed and you should send it to a repair activity for cleaning, overhaul, and recalibration. You should have a spare governor so that the engine can be operated during the governor overhaul period and other PMS that require removal of the original governor.
