PIN AS 1382470 - Caterpillar

Woodward UG8 Governors
SCHEMATIC OF UG8 DIAL GOVERNORWoodward UG8 Dial Governor
The UG8 Dial Governor is a mechanical-hydraulic governor. A hydraulic activated power piston is used to turn the output terminal shaft of the governor. A lever on the terminal shaft is connected to the fuel rack by a linkage rod. The governor has a separate oil supply and oil pump. The governor oil pump and ballhead are driven from a shaft in the governor drive housing. The shaft is driven by the variable timing drive assembly.The oil pump gives pressure oil to operate the power piston. The drive gear of the oil pump has a bushing in which the pilot valve plunger moves up and down. The driven gear of the oil pump is also the drive for the ballhead.An accumulator is used to keep a constant oil pressure of approximately 120 psi (830 kPa) to the top of the power piston and to the pilot valve.The power piston is connected by a lever to the output terminal shaft. There is oil pressure on both the top and bottom of the power piston. The bottom of the piston has a larger area than the top.Less oil pressure is required on the bottom than on the top to keep the piston stationary. When the oil pressure is the same on the top and bottom of the piston, the piston will move up and cause the output terminal shaft to turn in the increase fuel direction. When the oil pressure on the bottom of the piston is directed to the sump, the piston will move down and cause the output terminal shaft to turn in the decrease fuel direction. Oil to or from the bottom of the power piston is controlled by the pilot valve.The pilot valve has a pilot valve plunger and a bushing. The bushing is turned by the governor drive shaft. The rotation of the bushing helps reduce friction between the bushing and the plunger. The pilot valve plunger has a land that controls oil flow through the ports in the bushing. When the pilot valve plunger is moved down, high pressure oil goes to the bottom of the power piston and the power piston will move up. When the pilot valve plunger is moved up, the oil on the bottom of the power piston is released to the sump and the power piston moves down. When the pilot valve plunger is in the center (balance) position, the oil port to the bottom of the power piston is closed and the power piston will not move. The pilot valve plunger is moved by the ballhead assembly.The ballhead assembly has a ballhead, flyweights, speeder spring, thrust bearing, speeder plug and speeder rod. The ballhead assembly is driven by a gear and shaft from the driven gear of the oil pump. The speeder rod is fastened to the thrust bearing which is on the toes of the flyweights. The speeder rod is connected to the pilot valve plunger with a