developed in the engine to drive the shaft is transmitted from the
sun gear (11) through the reduction gear assembly. The attached
movable plate tends to rotate with the assembly. However, this
mechanically limited radial movement positions the steel balls
against the conical sockets of both plates, resulting in the movable
plate being axially directed rearward in the assembly.
The plate, moving rearward, contacts the torquemeter valve
plunger, opening the valve and allowing oil to flow into the
cylinder. This contact is maintained during all engine operation,
and the size of the valve opening varies as the plate moves rearward
or forward. As torque continues to increase and the torquemeter
valve opens further, oil pressure increases in the cylinder but will
not exceed the boost pump pressure because of the metered bleed (13).
The oil pressure developed in the cylinder exerts pressure
against the piston (movable plate), restraining the rearward
movement. With the engine operating in a steadystate condition the
cylinder oil pressure and movement of the plate hold in an equalized
position.
A factor affecting torque indications is the air pressure that
develops in the inlet housing at high power settings. This air
pressure produces a force oh the forward face of the piston (movable
plate) inducing a higher torque indication than is actually being
delivered. From the port on the forward face of the accessory drive
gearbox, the air pressure is vented to the airframemounted
torquemeter transmitter.
The pressurized oil from the torquemeter cylinder is also
directed to the transmitter from a port at the 3 o'clock position of
the inlet housing. The transmitter cancels the air pressure effect,
resulting in a true torquemeter indication at the instrument in the
cockpit.
A powerdriven rotary (booster) pump, containing pressure and
scavenge elements is mounted on and driven by the overspeed governor
and tachometer drive assembly. Each element is an individual pumping
unit and draws oil from a separate source. The pressure element
receives engine lubricating oil and delivers it, at a boosted
pressure, to the torquemeter valve. Excess oil flows back to the
inlet side of the pump. A relief valve in the overspeed governor and
tachometer drive assembly sets the powerdriven rotary (booster) pump
outlet pressure. The scavenge element receives oil from the
overspeed governor and tachometer drive gear housing and delivers it
to the oil return passages in the inlet housing assembly.
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