Nakakita hydraulic remote valve control
Hydraulic remote control of valves
Instruction book for Nakakita's hydraulic remote valve control: butterfly valves on the main engine lube oil and ballast lines carry hydraulic cylinder actuators operated from a control unit in the engine room. A hand pump supplies the pressure; a manually operated 4-way valve per valve directs the oil to open or shut, and in-line flow meters show the open/shut position. The book describes the system, each component (4-way valve, relief combination pilot check valve, self-seal couplings with air purge), the butterfly valves and actuators, troubleshooting, safety and gasket handling.
Maintenance procedures
Operating a remote valve
- At the control unit set the 4-way valve of the required valve to OPEN or SHUT. p. 4
- Work the hand pump lever back and forth until the in-line flow meter shows the valve has moved fully. p. 4
- Return the 4-way valve to neutral. p. 4
Before maintenance on a valve actuator
- Make sure the pipe is depressurised and the valve is below 40 °C. p. 49
- Isolate power to solenoids and limit switches and shut off the hydraulic/air supply. p. 49
- Before opening a spring actuator, slacken the adjusting screw so the spring reaches free length. p. 49
Maintenance intervals
| Item | When | Action | Manual |
|---|---|---|---|
| Line pressure, gland and gasket leaks | daily | Check gauge, tighten gland or flange if leaking | p. 67 |
| Connection bolts | every 3 months | Check and tighten | p. 67 |
| Gaskets, packing and seat | 1–2 years or at dry dock | Dismantle, inspect, renew | p. 67 |
Faults and what to do
Technical specifications
| Normal hydraulic pressure | 5.5 MPa (max 7 MPa, test 10.5 MPa) | p. 2 |
|---|---|---|
| Hydraulic oil | ISO VG 32 hydraulic oil (e.g. Shell Tellus 32, Mobil DTE 13M) | p. 3 |
| Valve stem | install horizontal where possible — vertical stems wear the lower bearing | p. 28 |
| Hot valve | do not touch above 40 °C without gloves | p. 49 |
Source: manufacturer's manual “EM-43-2 REMOTE CONTROL EQUIPMENT FOR M-E L.O AND BALLAST PIPE LINE”, 97 pages. Page numbers refer to the original. Check against the manual on board before work.