HOSE 2726737 - Caterpillar

For purposes of description, the PGE and PGEV governors are considered to consist of three major functional sections: a basic governor section, a speed setting section, and a load control section.Basic Governing Section (Figure 3-1)
This section consists of an oil pump, two accumulators, a speeder spring, a flyweight head assembly, a thrust bearing, a pilot valve plunger, a rotating bushing, a buffer compensation system, and a power cylinder.The governor drive shaft passes through the governor base and engages the rotating bushing. The pump supplies pressure oil for operation of the basic governor section, the speed setting section, the load control system (except applications using a remote vane servo, or where engine oil is supplied to the control system), and all other auxiliary features or devices.A spring loaded accumulator and relief valve system maintains governor oil operating pressure. When operating pressure is reached the spring pressure is overcome and the oil is released to sump.Direction of rotation is normally determined by the engine manufacturer or Woodward Governor Company. Governor rotation is either fixed cw, fixed ccw, or reversible. Figure 3-1 shows the arrangement for reversible rotation with four check valves in the oil pump passages. For fixed rotation the four check valves are removed and two plugs are placed in two of the passages to allow only one direction of flow. Governors for locomotives are built for one direction of rotation.The governor drive rotates the oil pump and pilot valve bushing. The flyweight head assembly is driven by the rotating pilot valve bushing. A thrust bearing rides on top of the flyweight-head toes permitting the rotational motion between the downward force of the speeder spring and the upward force of the flyweights.The relative motion between the bushing and plunger minimizes static friction. There are several styles of flyweight head assemblies available. The exact style used depends upon the engine drive train to the governor. A solid head is used where the drive is relatively free of torsional vibrations. "Spring driven" and "spring driven oil damped" head assemblies are used to attenuate objectional levels of torsional vibration which may be imparted to the governor from the engine. These vibrations may originate from a source other than the drive itself but reach the governor through the drive connection. Unless minimized or eliminated, these vibrations are sensed as speed changes and the governor will continually adjust the fuel rack in an attempt to maintain a constant speed.The greater of two opposing forces moves the pilot valve plunger up or down. Flyweight force tends to lift the plunger while speeder spring force tends to lower the plunger. When the engine is on speed at any speed setting, these forces are balanced and the flyweights assume a vertical position. In this position, the control land on the pilot valve plunger is centered over the regulating port(s) in the rotating bushing. No oil, other than leakage make up, flows to or from the buffer compensation system or power cylinder. A change in either of these