Subtopic: I.C. engine systems – fuel, cooling, lubrication, ignition, electrical, intake and exhaust
Question Statement:
Which of the following statements regarding the forced-feed (full pressure) lubrication circuit in farm tractors is/are correct?
Options:
(A) A positive displacement gear pump delivers oil under pressure through a full-flow filter to the main gallery.
(B) A spring-loaded pressure relief valve prevents excessive system oil pressure by bypassing surplus oil back to the sump at high RPM.
(C) An oil filter bypass valve opens automatically if the filter element becomes clogged, ensuring critical bearings are not starved of oil.
(D) Under-piston oil spray nozzles help extract heat from the piston crowns in heavy-duty turbocharged engines.
Answer Key:
A, B, C, D
Step-by-Step Solution & Explanation
All four statements represent standard tractor engine lubrication features:
• Gear pump delivers pressurized flow to engine galleries (A is correct).
• Relief valve controls maximum line pressure (B is correct).
• Filter bypass valve prevents catastrophic lubrication starvation if the paper element plugs (C is correct).
• Piston cooling jets spray oil directly onto piston undercrowns (D is correct).