Figure 1-2. Power Shift - Hydraulic Schematic

TM 10-3930-644-14&P

Figure 1-2. Power Shift - Hydraulic Schematic

In normal Lift Truck operation the turbine turns at a

encounters a resistance, and it takes power (from the

slower speed than the impeller an since both are the

engine) to keep the Impeller running against this

same dimension, the centrifugal force on the oil in the

resistance. in the turbine the oil is slowed down and

impeller is always greater than that of the oil in the

presses forward against the vanes, and when the turbine

turbine. It is this difference plus the pressurized oil from

is moving under this force, power to drive the truck is

the pump which causes the oil to circulate in and through

produced. Thus, all the oil passing through the impeller

the converter.

picks up energy and gives it to the turbine. Up to this

point operation is the same as a fluid coupling and there

From the above it can be seen that the oil in the

converter has a dual motion. It travels with the impeller

and the turbine around the outer circumference of the

To transmit velocity to the oil at the inner circumference

converter and it also flows around the inner

of the converter, a third member, the stator, is added to

circumference or central core of the converter. As a

the fluid coupling, between the impeller and the turbine.

result of these motions the oil carries a certain amount of

It is here that the fluid coupling becomes a torque

kinetic energy. The velocity of the oil in the converter

converter. With the impeller rotating and the turbine

increases as the oil passes through the impeller to the

stalled, the oil is driven through the curved blades of the

turbine and decreases as it passes through the turbine

turbine.

The curved blades redirect the oil in the

back to the impeller.

opposite direction from which it was received. As the oil

leaves the turbine blades, it strikes the stator blades

Since the velocity increases in the impeller, its kinetic

causing a reaction which produces torque multiplication.

energy increases and this gain in kinetic energy can

come only from the impeller. That is to say, when

The stator directs the oil back to the Impeller where any

increasing the velocity of oil in its vanes, the impeller

remaining kinetic energy combines with the kinetic

energy of the impeller oil,

R-171-1

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