Woodward UG-10 Dial, Installation And Operation Manual, Page: 23 / 62

Manual 03040 UG Dial Governor
Woodward 17
Increase in Load
When an increase in load occurs and the same fuel setting is maintained, speed
decreases. This generates the following sequence of governor movements:
1.
As speed decreases, the centrifugal force of the flyweights (24) decreases
and the opposing speeder spring (25) force is now greater than the
centrifugal force of the flyweights (24).
2.
The flyweights (24) tip inward and lower the speeder rod (21) and the right
end of the floating lever (31).
3.
This lowers the pilot valve plunger (39), opening the control port in the
rotating bushing (38). Pressure oil is released through the control port into
the lower cylinder of the power piston (9).
4.
The power piston is forced upward by the pressure oil acting on the larger
lower surface area of the power piston, and the governor output shaft is
rotated in the increase fuel direction.
5.
Linkage from the governor output shaft (6) lifts the compensating adjusting
lever (22), which rotates at the fulcrum (18), lowering the large dashpot
compensation piston (34).
6.
Pressure oil is applied to the bottom side of the small dashpot compensation
piston (35), raising the left end of the floating lever (31).
7.
This raises the pilot valve plunger (39) closing the control port (37).
8.
As pressure oil flows through the needle valve (33) from 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
increased fuel position. This is the position needed to run the prime mover
at the selected speed setting with the new load.
In both cases, a decrease or increase in load, the compensation system operates
in opposite directions. The compensation or amount of movement of the large
dashpot compensation piston (34) is controlled by the compensation adjustment,
that is, the position of the fulcrum (18).
The rate at which the small dashpot compensation piston (35) is returned to
normal is controlled by the needle valve adjustment, that is, the rate of flow of oil
through the needle valve (33).