The returning oil from the power cylinder ows, passing through the cylinder port R, groove ⑪
in the valve housing, oil hole ⑰ in the sleeve, groove ⑲ in the spool, oil hole
22
in the sleeve, and
groove ⑧ in the valve housing, back to the oil tank.
(c) When steering wheel is turned clockwise
As the steering wheel is turned clockwise, the
grooves in the spool shift to the right in relation to
the oil holes and grooves in the sleeve so that oil
holes ④ in the spool get out of line with holes ③
in the sleeve. The oil that has owed into groove
② thus far begins to ow into oil hole ⑫ in the
sleeve and then flows through grooves
23
and
⑬ in the spool, oil hole ⑭ in the sleeve, and oil
passage ⑮ in the valve housing to the hydraulic
motor. The hydraulic motor thus rotates in the
clockwise direction and the oil discharged from
the hydraulic motor ows through oil hole ⑭ in
the sleeve, groove ⑯ in the spool, and oil hole ⑰
in the sleeve to the cylinder port R in the housing
and thus actuates the power cylinder.
The returning oil from the power cylinder
ows, passing through the cylinder port L, groove
⑩ in the housing, oil hole ⑱ in the sleeve, groove
⑲ in the spool, oil hole
22
in the sleeve and
groove ⑨ in the housing back to the oil tank.
(2) Relationship between the rotating speed and operating force of the steering wheel
The force required to operate the orbitrol is basically a valve operating force (the force
required to compress the centering spring: 2.9 N-m {0.3 kgf-m} [2.14 lbf-ft]). That is, there is
no mechanical linkage between the steering wheel and the tires, and thus the operating force of
the steering wheel remains constant regardless of the rotating speed of the steering wheel. The
discharge of oil from the orbitrol rotor to the steering cylinder is 80 cm
3
/revolution.
(3) Neutral feedback of orbitrol
The neutral feedback function of the orbitrol is performed by the valve switching over the oil
passages according to the reaction force of the centering spring. (If the steering wheel is turned and
then released with the engine turned off, it will automatically return to the straight-ahead position.)
Should the neutral feedback not function properly, the steering wheel might turn by itself when the
operator does not turn it.
Fig. 6A.10
6A. STEERING SYSTEM (ORBITROL type)
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