Subtopic: Three point hitches – free link and restrained link operations
Question Statement:
Which of the following statements regarding the operational modes of tractor three-point hitch hydraulic control systems is/are CORRECT?
Options:
(A) Position control maintains the implement at a fixed vertical height relative to the tractor chassis, regardless of draft changes
(B) Draft control senses draft changes and automatically raises the implement to reduce load during tough soil conditions
(C) Position control is ideally recommended for soil-engaging primary tillage implements like mouldboard ploughs in undulating topography
(D) Mixed (blend) control combines draft sensing and position limits to prevent implement from digging too deep in sandy pockets
Answer Key:
A, B, D
Step-by-Step Solution & Explanation
- **A is correct:** Position control locks implement depth/height relative to the tractor chassis (used for rotavators, sprayers, seed drills).
- **B is correct:** Draft control uses top-link or lower-link feedback springs to maintain constant draft load on the engine.
- **C is incorrect:** In undulating terrain, position control causes excessive gouging on humps and lifting out of depressions; draft control is the correct mode for ploughing.
- **D is correct:** Mixed control allows draft sensing while setting a lower position floor limit.