Case MX210, MX230, MX255, MX285 Tractor Service Manual

Description

Table of Contents

1. General
2. Engine
3. Fuel
4. Electrical
5. Steering
6. Power Train
7. Brakes
8. Hydraulic
9. Chassis
10. Controller System
11. Schematics
12. Loctite Product Chart
13. A/C Temperature Poster
14. Cab climate control
15. Electrical System
16. Platform, cab, bodywork and decals
17. Special Tools

Manual Extract: REMOTE VALVE PROPORTIONAL CURRENT CONTROL (PCC) SOLENOID OPERATION

There is a proportional solenoid mounted on each end of a remote valve section. Each proportional solenoid is supplied with 335 to 345 PSI (23 to 24 bar) pilot pressure from the regulated pressure circuit. When the remote valve control lever is in the neutral position the proportional solenoid valve blocks the regulated pressure supply and drains the spool end cavities to tank.

When the remote control lever is moved down to the extend/raise position, the remote controller sends a current supply to the extend/raise proportional solenoid. The proportional solenoid valve does not just turn ON and OFF, but sets and maintains a pressure in the spool end cavity. The spool will shift to the left compressing the opposite side return springs. When the spring force equals the hydraulic force the spool stops and maintains that position.

The distance that the spool will shift is determined by the flow control setting for that remote section.
Increasing the flow control setting will increase the current supply to the proportional solenoid, which in turn increases the hydraulic pressure in the spool end cavity. The increased pressure moves the spool further to the left, until the spring force once again equals the hydraulic force. The spool will maintain the new position (flow setting) until the flow control setting is changed again, or the remote control lever is moved to neutral.

When the remote control lever is moved to neutral the current supply is cut off, the proportional solenoid valve shifts opening the spool end cavity to tank. The return springs center the valve spool in the neutral position.