Woodward UG-10 Dial, Installation And Operation Manual, Page: 33 / 62

Manual 03040 UG Dial Governor
Woodward 27
Definitions
Use the troubleshooting chart (Table 5-1) on the following pages to determine the
probable causes of faulty operation and to correct these problems.
Terms used in the chart are defined as follows:
Hunt— A rhythmic variation of speed which can originate in the governor or in the
prime mover. (See Table 5-1, Par. 1A, for troubleshooting information.) A hunt
usually has a frequency of less than 5 cycles per minute.
Surge— A sudden variation of speed occurring at periodic intervals which can
also originate in the governor or in the prime mover. (See Table 5-1, Par. 1A, for
troubleshooting information.)
Jiggle— A high frequency vibration of the governor output shaft and fuel linkage.
Do not confuse this with normal controlling action of the governor. A jiggle has a
frequency of more than 50 cycles per minute.
Preliminary Inspection
Governor problems are usually revealed in speed variations of the prime mover,
but it does not necessarily follow that such variations are caused by the
governor. When improper speed variations appear, the following procedure
should be performed:
1.
Check the load to be sure the speed changes are not the result of load
changes beyond the capacity of the prime mover.
2.
Check engine operation to be sure all cylinders are firing properly and that
the fuel injectors are in good operating condition and properly calibrated.
3.
Check the linkage between the governor and fuel racks or valve. There must
be no binding or lost motion.
4.
Check the setting of the needle valve and compensation adjustment. (See
Chapter 4, Compensation Adjustments.)
5.
Check that the oil is clean and oil level is correct at operating temperature.
The source of most problems in any hydraulic governor stems from dirty oil.
Grit and other impurities can be introduced into the governor with the oil, or
form when the oil begins to break down (oxidize) or becomes sludgy.
The internal moving parts are continually lubricated by the oil within the unit.
Valves, pistons, and plungers will stick and even “freeze” in their bores, due
to grit and impurities in the oil.
If this is the case, erratic operation and poor response can be corrected (if
wear is not excessive) by flushing the unit with fuel oil or kerosene.
The use of commercial solvents is not recommended as they may damage
seals or gaskets.
Change the oil and flush the governor twice a year if possible.