Subtopic: Hitch systems and hitching of tillage implements
Question Statement:
Regarding three-point hitch linkages and the virtual hitch point (VHP) of a tractor-implement system, which of the following statements are CORRECT?
Options:
(A) In the vertical longitudinal plane, the VHP is the intersection point of the top link centerline and the lower link centerline
(B) Placing the VHP below and behind the tractor rear axle increases tractor front-end instability
(C) Draft control automatically adjusts implement depth by sensing compressive forces on the top link or tensile forces on lower links
(D) Position control maintains the implement at a constant depth relative to the tractor chassis regardless of soil resistance variations
Answer Key:
A, C, D
Step-by-Step Solution & Explanation
1. The virtual hitch point (VHP) in the longitudinal vertical plane is defined by the intersection of the line passing through the top link and the line passing through the lower links. (Statement A True)
2. Positioning the VHP above the ground and ahead of the rear axle provides downward pitch and aids traction while maintaining steering stability. Placing it excessively high or improperly oriented can induce rearing. (Statement B False)
3. Draft control senses linkage forces (compression in top link or tension in lower draft links) via torsion bars or spring packs and actuates the hydraulic spool valve to raise the implement when draft increases. (Statement C True)
4. Position control holds the rockshaft and implement at a fixed predetermined position relative to the tractor frame regardless of varying soil draft. (Statement D True)