When the pilot valve plunger is lowered, oil
The 3161 Standard and Torque Rise Governors
under high pressure moves through the control port of
are designed to operate with a 2 to 8 percent droop and
the bushing, to the bottom side of the power piston, and
have an internal droop pivot pin adjustment.
the piston moves up. When the pilot valve plunger is
raised, the oil from the bottom of the power piston is
The 3161 Generator Set Governor is designed to
released to sump, and the higher oil pressure on top of
operate with a 0 to 4 percent droop. It has an external
the piston moves the piston down. When the engine is
adjustment lever connected to the internal droop pivot
running at a steady state, the control land of the pilot
pin. This permits droop adjustments to be on the outside
valve plunger covers the ports in the ballhead bushing
of the governor housing.
and the power piston does not move. The movement of
Torque Rise Control
the pilot valve plunger is controlled by the ballhead
The ballhead system has a ballhead, flyweights,
speeder spring, thrust bearing, and speeder plug. The
ballhead, as part of the pilot valve bushing, is turned by
the drive coupling and drive shaft.
As the ballhead turns, the centrifugal force
causes the flyweights to pivot outward. At the same
time, the force of the speeder spring pushes the thrust
bearing down on the flyweight toes against the
centrifugal force of the flyweights. When the speeder
plug is pushed down this increases the downward
pressure on the speeder spring, and the governor speed
setting is increased. The engine then runs at a higher
speed and puts a higher centrifugal force on the
flyweights to equal the speeder spring force and put the
TORQUE RISE COMPONENTS
system back in balance.
1. Torque control lever. 2. Cam.
Speeder spring force or speed setting is
controlled through the speed setting shaft.
The torque rise control consists of a cam that
makes the governor give more fuel to the engine under
The compensation system has a needle valve
Different percentages of torque rise can be
and a buffer piston with two springs. This system can be
selected by changing the cam to a programmed rate of
adjusted to give the desired rate of governor control and
rise. This change can be made on or off the engine.
engine speed stability. Since the governor makes an
Cam selection and high idle settings must be based on
adjustment rapidly to a change in engine load or speed
setting, the engine can go into a "hunt" condition
The torque rise control is factory installed. It is
(temporary increase and decrease in engine speed) if
not practical to install it in the field.
too much adjustment is made. The purpose of the
The torque rise cam has three distinct profiles:
compensation system is to prevent overcorrection to the
the base circle area (3); the approach ramp area (4); and
engine load or speed setting change. The system uses
the cam lift area (5).
a pressure differential that is applied across the
The "base circle area" is a radius that does not
compensation land of the pilot valve plunger to give a
lift the cam follower.
The cam follower must be
stable governor control.
positioned on the base circle area when the dial indicator
is zeroed, for a check or adjustment of the torque rise
The 3161 Governor is an isochronous governor
with the ability to operate with droop by the adjustment of
The "approach ramp area" is the "transition
an internal droop pivot pin. The governor may be used
area" from the base circle to the cam lift area.
with droop to allow for load division between two or more
The "cam lift area" is the area on the cam that
engines connected to a single shaft, or for operating in
lifts the cam follower and torque rise pilot valve lever,
which allows additional fuel for torque rise greater than
The speed droop of a governor is the percent
the natural torque rise of the engine.
that the engine speed drops between high idle and full