TM 5-2410-241-23-1
0011
IMPLEMENT AND STEERING HYDRAULIC SYSTEM CONTINUED
During a normal left turn, oil from the steering control valve flows into the valve port (Figure 21, Item 5) and through
the stem (Figure 21, Item 6) to the check valve (Figure 21, Item 3). Oil also flows through passage (Figure 21,
Item 4), around the stem (Figure 21, Item 6), and through the orifice (Figure 21, Item 2) into the chamber (Figure
21, Item 1). Oil opens the check valve (Figure 21, Item 3) flows through the stem (Figure 21, Item 6), through the
passage (Figure 21, Item 18), and to the motor port (Figure 21, Item 16). Oil then flows through the steering motor
and the oil turns the steering motor clockwise. Oil flows through the motor to the motor port (Figure 21, Item 15).
The motor port (Figure 21, Item 15) sends oil through the passage (Figure 21, Item 13) to the check valve (Figure
21, Item 9). Oil at the check valve (Figure 21, Item 9) is temporarily blocked and the pressure of the oil increases.
When the oil pressure reaches a threshold of approximately 1,015 psi (7,000 kPa), the stem (Figure 21, Item 6)
moves to the right. Now, oil in the passage (Figure 21, Item 13) flows through passages (Figure 21, Item 12) and
through the stem (Figure 21, Item 6) to the valve port (Figure 21, Item 7) and to the tank.
As the stem (Figure 21, Item 6) moves to the right, oil in the chamber (Figure 21, Item 11) is sent through an orifice
(Figure 21, Item 10) to a passage (Figure 21, Item 8). The oil flows through the valve port (Figure 21, Item 7) to the
tank. Once the stem (Figure 21, Item 6) has moved approximately 0.08 inch (2 mm), oil in the chamber (Figure 21,
Item 11) flows directly through a passage (Figure 21, Item 8) and the valve port (Figure 21, Item 7) to the tank and
the stem is allowed to move faster to the right.
During overspeed conditions, feedback torque that comes through the steering gears attempts to turn the steering
motor at a faster speed than the speed that is necessary. This feedback causes reduced pressure on the inlet side
of the counterbalance valve command valve port (Figure 21, Item 5), passage (Figure 21, Item 18), and motor port
(Figure 21, Item 16). When the inlet pressure decreases lower than threshold pressure, the stem (Figure 21,
Item 6) moves to the left. The flow of oil through the outlet side of the counterbalance valve motor port (Figure 21,
Item 15), passage (Figure 21, Item 13), and valve port (Figure 21, Item 7) is restricted. The restricted oil flow
counteracts the feedback torque that drives the steering motor. Now, the steering motor speed is sustained close
to the speed that is demanded by the steering control valve.
Crossover relief valves (Figure 21, Items 14 and 17) prevent damage to the steering system from pressure
increases (spikes). These valves are pilot controlled relief valves that open at approximately 6,000 psi
(41,500 kPa). When the crossover relief valves open, the valves send oil to the opposite motor port.
Figure 21. Counterbalance Valve (Steering).
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