Woodward UG-10 Dial, Installation And Operation Manual, Page: 22 / 62

UG Dial Governor Manual 03040
16 Woodward
Changes in governor speed setting produce the same governor movements as
do changes in load on the engine. The description that follows is based upon
speed changes caused by load changes.
Decrease in Load
When the prime mover is running on speed, the flyweights (24) are in a vertical
position for normal steady state operation. The pilot valve plunger (39) is
centered over the control port of the rotating bushing, and the control land stops
the flow of pressure oil through the bushing (38) control port. There is no
movement of the power piston (9), and no movement of the governor output shaft
(6).
When a decrease in load occurs and the same fuel setting is maintained, speed
increases. This generates the following sequence of governor movements:
1.
As speed increases, the centrifugal force of the flyweights (24) increases
and becomes stronger than the force of the speeder spring (25).
2.
The flyweights (24) tip outward and raise the speeder rod (21) and the right
end of the floating lever (31).
3.
This raises the pilot valve plunger (39), opening the control port in the
rotating bushing (38). Oil is released from the bottom of the power piston (9)
to sump.
4.
Pressure oil on the top side of the power piston (9) moves it downward,
rotating the governor output shaft in the decrease fuel direction.
5.
Linkage from the governor output shaft (6) lowers the compensation
adjusting lever (22), which rotates at the fulcrum (18), raising the large
dashpot compensation piston (34).
6.
Suction is thus applied to the chamber of the small dashpot compensation
piston (35), lowering the left end of the floating lever (31).
7.
This lowers the pilot valve plunger (39) closing the control port (37).
8.
As sump oil flows through the needle valve (33) from the sump into the
dashpot compensation piston assembly (34 and 35), the small dashpot
compensation piston (35) is returned to its normal centered position by the
compensation spring at the same rate as the speeder rod (21). This keeps
the pilot valve plunger (39) in its centered position.
9.
The control port in the rotating bushing (38) is kept closed by the land on the
pilot valve plunger (39).
10. This stops the governor output shaft and power piston movement in the new
decreased fuel position. This is the position needed to run the prime mover
at the selected speed setting with the new load.