Installation Instructions

B1700·B21 00·B2400 WSM, 11770
[3] OIL FLOW
• Neutral Position
[=:J Low Pressure
B177F703
7 STEERING
@@
(A)
From Pump (Through Flow
+
+
Priority Valve)
I
(B)
To HST Unit (HST Type) or
5
Transmission Case (Manual
Transmission Type)
(1 )
Sector Gear Shaft
(2)
Ball Nut
(3)
Worm Shaft
(4)
Reaction Pistons
(5)
Centering Spring
(6)
Valve Housing
(7)
Spool
When the steering wheel is not turned, the valve is
placed in the neutral position by the centering
springs (5) and pressurized reaction pistons (4).
Therefore, there is no difference betwee,n
• Left Turning
pressures on the right and left cylinder chambers.
And the ball
nut (2) and sector gear shaft (1) do not
move. So, the front wheels keep the direction.
©©
High Pressure
[=:J Low Pressure
B177F704
10
(1 )
Sector Gear Shaft
(2)
Ball Nut
(3)
Worm Shaft
(4)
Thrust Race
(5)
Reaction Piston
(6)
Centering Spring
(7)
Valve Housing
(8)
Spool
(9)
Ball
(10)
Relief Valve
(A)
Chamber "A"
(B)
Chamber "B"
(C)
From Pump
(0)
To HST Unit or
Transmission Case
(a)
Port "a"
(b)
Port "b"
1. When the steering wheel is turned
counterclockwise, the worm shaft (3) is also
turned.
However,
front wheel load stops sectors gear
shaft
(1) and ball nut (piston) (2) from moving,
and only
worm shaft (3) turns counterclockwise.
Then, due
to the reaction, the worm shaft (3)
moves upward a little. And the thrust race (4)
pushes the spool (8), reaction piston (5) and
centering springs (6).
2. At this time, the oil passage from pump to port
"b" and oil passage from port "a" are closed.
Therefore, the pressure-fed oil from pump
flows
to the chamber "A" through port "a". Thus, the
ball nut (piston) (2) is pushed, and the sector gear
shaft (5) is rotated in the direction of the arrow.
7-M3