Subtopic: Steering and hydraulic control systems used in tractors
Question Statement:
In fully hydrostatic power steering systems of modern agricultural tractors, the steering wheel is mechanically connected to which hydraulic control element?
Options:
(A) A mechanical drag link and drop arm
(B) An Orbitrol rotary metering valve unit that directs pressurized oil to a double-acting steering cylinder
(C) The engine intake camshaft gear
(D) The rear differential crown wheel
Answer Key:
B
Step-by-Step Solution & Explanation
- **Hydrostatic Steering Principle:** In hydrostatic steering, there is no mechanical linkage (drag link, tie rods to steering column) connecting the steering hand wheel to the front axle.
- The steering wheel shaft directly rotates an **Orbitrol unit** (a fluid rotary metering device combining a spool control valve and a gerotor pump), which ports measured hydraulic flow to the front steering ram.