500 CSD Gear Differential and Hydraulic Unit Schematic
Feb 15/67 Figure 3 (Sheet 2) 24-11-0
Page 9
BOEING PROPRIETARY - Copyright . - Unpublished Work - See title page for details.
4. Governing System
A. The basic governor is a spring-biased, flyweight-operated hydraulic control valve. It functions to control porting of transmission charge oil to the control cylinder. (See figure 2.) The rotating sleeve in the governor is driven by the output gear and hence is responsive to transmission output speed. Flyweights pivoted on this sleeve move a valve stem located within the sleeve against the bias of a spring. During steady state operation, supply pressure is reduced to the required control pressure by orificing action at the edges of the stem control groove. Depending on valve stem position, charge oil is ported to the control piston or control oil is drained to the transmission case.
B. The control cylinder is the actuator which responds to the porting functions of the governor. The affective area of the spring loaded side of the piston in the control cylinder is considerable less than the opposite end. Therefore, the piston will compress the spring with equal pressure on both sides of the piston. (See VIEW 1, figure 2.) When the governor allows the oil to drain from the control cylinder as in VIEW 2, the spring assisted by charge pressure on the small area of the piston allows the spring to relax. Small increments of such piston movements results in speed control within narrow limits.
5. Hydraulic System
A. The hydraulic system consists of the charge pump, the scavenge pump and the charge relief valve. (See figure 2.)
B. The charge pump is located in the hydraulic circuit between the al1- attitude reservoir and the transmission. The charge pump supplies oil to the cylinder blocks, governor, control piston, and the lubricating system.
C. The scavenge pump is located in the hydraulic circuit between the transmission sump and the external oil cooler. The scavenge pump picks up lube oil and internal leakage and pumps it through the external oil cooler into the al1-attitude reservoir.
D. The charge relief valve regulates the operating pressure of the charge oil system. (See figure 2.) The valve accomplishes this function by metering the discharge of oil from the charge oil system to maintain the preset charge pressure. The charge pump draws oil from the reservoir and delivers a constant volume of oil to the charge relief valve cylinder. The piston in the relief valve cylinder is moved back by oil pressure compressing the spring. Oil is bled to the scavenge lime as determined by spring pressure against charge pressure acting on the piston. The oil under charge pressure is used for control in the governor and control valve and to replenish the oil used in the multiple piston hydraulic units through the stationary port plate.
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24-11-0 Page 10 BOEING PROPRIETARY - Copyright . - Unpublished Work - See title page for details. Feb 15/67
6. All-Attitude Reservoir and Air Separator
A. The all-attitude reservoir performs the following functions:
(1)
Separate entrained air from the system oil.
(2)
Provide a supply of deaerated oil to the transmission through a wide range of acceleration loadings and aircraft attitudes. The reservoir contains no moving parts, and performs its functions automatically, utilizing the energy of the transmission scavenge oil.
B. Scavenge oil pumped thru the cooler returns to the transmission reservoir via the swirl chamber. This return oil, which is highly aerated, enters the swirl chamber at high velocity through a tangential inlet, causing a swirling action which creates a vortex within the swirl chamber. Air entrained in the entering oil, having a lower density than the oil, moves to the center of the vortex and escapes the case. The oil, relieved of its entrained air, moves along the wall of the swirl chamber and out into the reservoir. (See figure 2.)
C. As described above, return oil is always deaerated and ported to the reservoir, regardless of transmission attitude. The inlet suction port is located in approximately the center of volume of the reservoir, and the volume of oil contained within the reservoir is such that, regardless of transmission attitude, the inlet port will always be surrounded by oil. (See figure 2.) Static pressure in the reservoir is approximately the same as case pressure.
7. Integral Oil or Charge Filter and Filter Bypass
A. The integral or charge filter is equipped with a bypass around the filter element to ensure a flow of oil in case the element becomes completely clogged. On some CSD units with plain filter caps, the bypass valve is inside the filter element. On later CSD units, the bypass or relief valve is located in the integral oil filter cap assembly. The filter has a mechanical snap-out indicator to show when the filter is clogged.
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