Governor Preparation

ELECTRIC SHUTDOWN 1. Electric shutdown assembly.

There is a diode used in the circuit for the electric solenoid because it is polarity sensitive. If the wires are connected the wrong way the solenoid will not operate.

The electric shutdown can be used by itself, or in addition to the manual and pressure shutdown controls. If this shutdown is added after the governor has been shipped from the factory, an adjustment must be made. See TESTING AND ADJUSTING section for the correct adjustment.

When the electric shutoff is used by itself, a small cover and gasket must be installed on top of the shutdown assembly.

PNEUMATIC SPEED SETTING CONTROL

The pneumatic speed setting control is installed on the left front corner of the governor top cover. Because of its design, it is not practical to add the pneumatic speed control on the 3161 Governor in the field.

System air pressure from a remote throttle and internal pressure oil from the governor operate the control to increase or decrease the speed at which the engine runs. This control has the ability to repeat constant speed settings over a large range of conditions.

The pneumatic speed setting control has a standard air pressure range of 70 to 415 k Pa ( 10 to 60 psi). Special applications of this control can use a pressure range of 35 to 380 kPa (5 to 55 psi) or 35 to 620 kPa (5 to 90 psi).

Increase Engine Speed

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As control air pressure enters the speed setting bellows through the inlet port, expansion of the bellows takes place. The bellows pushes down on the speed setting lever to the left of the pivot. This lifts the right end of the speed setting lever against the feedback spring force to close the nozzle to drain.

Supply oil flows through an orifice to the lower side of the speed setting pilot valve plunger and then to drain through the nozzle. When oil flow from the nozzle is stopped by the speed setting lever, oil pressure increases and the speed setting pilot valve plunger moves up. This lets control oil go to the top of the speed setting piston. As the control oil pressure increases, the speed setting piston moves down to increase the governor speed setting through a rod and lever connected to the governor speed setting shaft.

As the speed setting piston moves down, the feedback spring is put under compression and pushes the speed setting lever away from the nozzle. Control oil can now go to drain and the pilot valve loading spring pushes the pilot valve plunger down to stop oil flow to the top of the speed setting piston. This results in the speed setting piston stopped in a new position that is proportional to the air pressure supplied to the speed setting bellows.

Decrease Engine Speed

When the control air pressure is lowered, the speed setting bellows moves back toward its original position. The feedback spring now pushes the speed setting lever away from the nozzle and control oil goes to drain through the nozzle.

As control oil pressure goes to drain, the oil pressure below the speed setting pilot valve plunger is decreased and the pilot valve loading spring moves the plunger down. This lets control oil above the speed setting piston go to drain and the feedback spring pushes the piston up. When the piston moves up, the force on the governor speed setting lever is lowered and the governor speed setting is reduced.

The speed setting piston moves up until the force of the feedback spring and the speed setting bellows moves the speed setting lever to close control oil to drain at the nozzle. At this time, the speed setting pilot valve plunger moves up to stop control oil movement above the speed setting piston. This results in the speed setting piston stopped in a new position that is proportional to the air pressure applied to the speed setting bellows.