PGEV and PGE Locomotive Governors. Manual - part 12

Manual 36703

PGEV and PGE Locomotive Governors

Woodward

When the governor speed setting is increased, the speed setting servo position
moves down. This action moves the floating lever down away from the fuel limit
lever so that the limit level no longer restricts fuel.

Figure 3-6b. Start Fuel Limiter Linkage

PGEV and PGE Locomotive Governors

Manual 36703

Woodward

Chapter 4.

Troubleshooting

Introduction

It is impossible to anticipate every kind of trouble that is encountered in the field.
This covers the most common troubles experienced. Poor governing may be due
to faulty governor performance, or it may be due to the governor attempting to
correct for faulty operation of the engine or turbine auxiliary equipment. The
effect of any auxiliary equipment on the overall control requirements of the
governor also must be considered.

Be prepared to make an emergency shutdown when starting the
engine, turbine, or other type of prime mover, to protect against
runaway or overspeed with possible personal injury, loss of life, or
property damage.

Oil

Fill the governor with oil to the mark on the oil level gauge with the engine idling.
Oil must be visible in the glass on the gauge during all other conditions.

Dirty oil causes approximately 50 per cent of all governor troubles. Use clean
new or filtered oil. Containers used to fill governors from bulk containers should
be perfectly clean. Oil contaminated with water breaks down rapidly, causes
foaming and corrodes internal governor parts.

Compensating Needle Valve

The compensating needle valve must be correctly adjusted with the governor
controlling the engine or turbine, even though the compensation may have been
previously adjusted at the factory or on governor test equipment. Although the
governor may appear to be operating satisfactorily because the unit runs at
constant speed without load, the governor still may not be correctly adjusted.

High overspeeds and low underspeeds, or slow return to speed, after a load
change or speed-setting change, are some of the results of an incorrect setting of
the compensating needle valve.

Definitions

Use the chart on the following pages to determine the probable causes of faulty
operation, and to correct these troubles. Terms used in the chart are defined as
follows:

Hunt

—A rhythmic variation of speed which can be eliminated by blocking

governor operation manually, but which will recur when the engine is returned to
governor control.

Manual 36703

PGEV and PGE Locomotive Governors

Woodward

Surge

—A rhythmic variation of speed, always of large magnitude, which can be

eliminated by blocking governor action manually and which will not recur when
the engine is returned to governor control, unless speed adjustment is changed
or the load changes.

Jiggle

—A high-frequency vibration of the governor fuel-rod end (or terminal

shaft) and fuel linkage. Do not confuse this with normal controlling action of the
governor.

Preliminary Inspection

Governor troubles 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

malfunctions in the vane servo, generator control circuits, switchgear, etc.

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 linkage between governor and fuel racks to be sure there is no

binding or excessive backlash.

4.  Check setting of governor compensation needle valve.

5.  Check speed-setting circuits for voltage level and sequencing.

6.  Check for fuel-pressure changes.

7.  Check governor oil pressure. A test port is provided in two sides of the

governor power case for this purpose.

8. The source of most troubles in any hydraulic governor stems from dirty oil.

Grit and other impurities can be introduced into the governor with the oil, or
can form when the oil begins to break down (oxidize) or become 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 excessive wear caused by grit and impurities in the oil. If this is the case,
erratic operation and poor response can be corrected 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. Remove the
cover, open the drain cock and drain out the oil. Flush the governor by filling
it with fuel oil. With the engine running at low speed, cycle the governor by
opening the needle valve two or three turns. Let the governor hunt for a
minute or two and then stop engine and drain the governor. Flush the
governor once again. Fill the governor with oil, pouring it over all the internal
parts that are visible. Start the engine and reset the compensation needle
valve.

9. Check drive to governor for any evidence of misalignment, roughness,

excessive backlash, etc.

PGEV and PGE Locomotive Governors

Manual 36703

Woodward

Table 4-1. Troubleshooting

Trouble Cause

Correction

Engine hunts or
surges.

Needle valve adjustment incorrect.

Adjust needle valve as described in
Chapter 2.

Buffer springs too light. This may occur
on a new installation; or on an old
installation because of a radical change
in load conditions.

Install heavier buffer springs (consult
Woodward Governor Company).

Lost motion in engine linkage, fuel
pumps, or gas valve.

Repair linkage, fuel pumps, or gas
valve.

Binding in engine linkage, fuel pumps,
or gas valve.

Repair and re-align linkage, fuel pumps,
or gas valve.

Governor stroke too short. This may
occur on a new installation. Should be
at least 50 percent of full governor
travel between idle and full load.

Redesign or rework the fuel linkage to
require more governor stroke. (Consult
engine manufacturer and Woodward
Governor Company).

Low oil level. No harm will be done if
top of oil is visible in gauge glass.

Add oil slowly to correct level in gauge.

Dirty oil or foaming oil in governor.

Drain governor oil; flush governor to
clean, and refill with proper clean oil.
Bleed air and adjust the needle valve.

Governor worn or not correctly
adjusted.

Try spare governor or repair and adjust
governor.
a.

Check flyweight pins and bearings
for wear.

Check flyweight toes for wear
and/or flat spots.

Check flyweight and head thrust
bearing; also centering bearing.

Pilot-valve plunger may be
sticking; clean and polish if
necessary.

Do not break corners of control land.

Check vertical adjustment of pilot
valve plunger and correct if
necessary.

Clean and polish all moving parts
to ensure smooth and free
operation.

Spring too weak in telescopic link.

Install heavier spring so that link stays
solid at all times.

2. Fuel pump racks do

not open quickly when
cranking engine.

Low oil pressure in governor.

Check governor pump gears and
gear pockets for excessive wear.
No correction except to replace
worn parts.

Flush governor and refill with
clean oil to remove dirt in pump
check valves.

Examine pump check valves. If
not seating tightly, install new
ones.

Cranking speed too low.

Install a booster servomotor (consult
Woodward Governor Company).

Booster servomotor (if used) not
functioning properly.

Check action of automatic air-
starting valve.

Check air and oil connections.

Shutdown nuts not adjusted correctly.

Loosen nuts and start engine. Readjust
nuts for proper clearance at idle.

Content .. 10 11 12 13 ..