Subtopic: Steering and hydraulic control systems used in tractors
Question Statement:
Which of the following statements comparing open-center and closed-center load-sensing (CCLS) hydraulic systems in farm tractors is/are correct?
Options:
(A) In an open-center system, a fixed displacement pump continuously circulates hydraulic fluid at low pressure through neutral open spool valves back to the reservoir when no actuators are operating.
(B) In a closed-center load-sensing system, a variable displacement pump delivers near-zero flow at high standby pressure when control valves are in neutral, saving substantial engine power.
(C) Closed-center systems can supply multiple hydraulic actuators simultaneously with load-independent flow sharing.
• Open-center circuits pump fluid continuously through open valves at low pressure (A is correct).
• CCLS systems use variable displacement swashplate pumps to eliminate neutral throttling heat (B and C are correct).
• Open-center circuits use simple fixed gear pumps, not expensive variable piston pumps (D is false).