Closed Center Hydraulic System
This is an arrangement that leaves no open path from pump to tank while the valves are in neutral, keeping the system permanently under pressure. It generally works with a variable displacement pump and a pressure regulator: when there is no demand the pump reduces flow to almost zero, and when a valve opens it delivers flow instantly.
The advantage of a closed centre is that movement speed is largely independent of engine speed and that multiple functions interfere with each other less. Because pressure is standing ready, the response is also shorter. In return the system is more complex and more sensitive to cleanliness.
- It is common on newer generation and high power tractors.
- Because it reduces pump stroke at idle, it does not produce unnecessary heat.
- When filter maintenance is neglected, the regulator and pump are damaged quickly.
Recognising this arrangement matters for retrofit kit selection. What the LFT20 and LFT54 require is not a particular hydraulic architecture but a quick-lift lever assembly pulled by a cable. On a modern tractor with a closed centre system and electronic hitch control there is no such cable; in that case the kit is not applicable. Confirm compatibility from the mechanism, not from the brand.
The context in which this term is used: Converting a tractor hydraulic lever to electronic control