DRAWBAR AS 5023879 - Caterpillar

Types
A Caterpillar Engines Electric Set is generally furnished with one of the following types of governors:
Mechanical approximately 3% speed droop (fixed)
Woodward UG8 Hydraulic Adjustable from 0% to approximately 4% speed droop
Woodward PSG Hydraulic Adjustable from 0% to approximately 4% speed droopTwo types of governors that are being used for special applications are the electric-hydraulic and electronic governors. These are adjustable from 0% to approximately 4% speed droop.Characteristics
The governors listed above include in their description a value of speed droop. Speed droop is defined as the percent change in engine speed between no load (high idle) and full load. Speed droop can be calculated using the equation given below.
Illustration 1 g01058906
A schematic of a typical mechanical governor is shown in Illustration 2. The basic components are a governor spring, a set of weights, and linkage connecting these components to the engine fuel rack.
Illustration 2 g01058910
Schematic of a typical Mechanical GovernorThe weights are driven by the engine through gears of an appropriate ratio. The engine speed control is set for the desired engine speed. This, in turn, compresses the governor spring and the fuel rack moves to a position to supply fuel to the engine. When the engine starts, the weights rotate. Since they are constructed to move under the action of centrifugal force, the weights move out as the engine speed increases. This action causes the toes of the weights to compress the governor spring further. This movement continues until the centrifugal force of the weights is in balance with the force of the compressed spring. When the weights move out against the force of the governor spring, the fuel rack setting is reduced. The engine speed will stabilize at a value where the spring force, weight centrifugal force, and engine speed are in balance.An electric set engine is customarily set at "High Idle" speed when there is no load on the generator. Generators rated 1200 rpm, 60 cycles will be used in the examples that follow.
Illustration 3 g01058916
Typical speed droop characteristics of a 3% mechanical governor. Line A represents an ideal 3% speed droop characteristic: Line B an actual speed droop characteristic and Line C the rated speed or frequencyIllustration 3 shows the speed droop characteristics of a 3% mechanical governor. In this case, high idle speed is 1236 rpm. Line "A" represents an ideal 3% speed droop characteristic. Line "B" represents an actual speed droop characteristic. Because of friction losses and limitations of materials, a governor speed droop characteristic is never a straight line. This is one reason why the descriptions of speed droop percentage include the word "approximately". The ideal speed droop characteristic figure of 3% will be used in this discussion. At 0% load, the engine speed or generator frequency is 103% of the rated value. This represents 61.8 cycles for a 60 cycle system. At 100% load the engine speed or generator frequency is 100% of rated value. This represents 60.0 cycles for a 60 cycle system. Speed characteristics will be given in per cent of