Handling proportional valves

Proportional valves repair part of provision cranes.

It is known that if you are subcontractor in a shipyard your job and the work you will provide will be harder. Why? I thought so…

I worked on both sides of the fence either as subcontractor and as shipyard employee. I know that a shipyard it’s a big organization with many employees and with different professional levels. A shipyard employee all the time is covered by the shipyard as entity and is learning to blame others. That’s why there are so many problems inside a shipyard. Like a subcontractor, shipyard will blame you for every mistake they’ll do. Sometimes they will find excuses to stop you from your work. Reputation is very important and neither one (subcontractor team and shipyard) wants to ruin it.

Ones, I attended in a dry dock to a tanker vessel for repair and service of the provisions cranes.

The job was quoted several days and the scope of job was overhauling and adjusting of proportional valves block control and load tests of the provision cranes.

First it was dismantled the hydraulic block control and was taken on the test bench of the workshop.

From the beginning the job sounded pretty simple but not all the simple things are going to stay like that specially in this area of ship repair.

The workshop was crowded with lot of work and the jobs were continuing coming. And because of that the test team was trying to cover all the jobs properly but in this case they didn’t succeeded.

After 2 or 3 days, I got the hydraulic block back to the cranes but after the installation some problems occurred. First leakage occurred, I found some broken o-rings and then the operation of the hydraulics proportional valve block wasn’t proper. Actually, the electrical activator was damaged and it was required to be renewed.

Finally, we manage to adjust the hydraulic load control system, conducted load test of the crane and cranes were OK.

In the end there were some alarming moments because one of the cranes wasn’t picked up load. I had to improvise and I had to remove the electrical connector and then the crane started to lift the load.

 
PVG 32 and 120 are hydraulic load control systems.

Proportional valves are constructed in modules and have the following items:

Pump side module PVP – The main line from the pump and the main line to the tank are connected to this module. Two pressure gauge outlets are mounted on this module where the most pressures are measured. The module contains a main pressure relief valve, which gives maximum pressure to all system. When the valve unit contains an electrical activator, PVE, the module includes a pressure reduction valve for the pilot pressure.

Basic module PVB – This module gives oil to different equipments including crane equipment. The valve contains a valve spool, which control the oil flow. The spool is controlled by the mechanical lever or the electrical connector. This module can also include LS (load sensing) pressure relief valves, which control the pressure for each oil flow direction individually. Pressure compensator check valves can also be installed.

Mechanical activation modules PVM – All basic modules PVB are fitted with a mechanical activator. The crane’s motions are controlled with this mechanical lever.

Electrical activation modules PVE – The basic modules can also be fitted with an electric activator. The crane’s motions are controlled with electric controls

End plate module PVS – This module is used as an end plate for the whole unit.

Main spool PVBS – The basic module can be equipped with different types of spool for different applications.

Cover PVMD – If the electric controls are inexistent this cover is used.

Anti-cavitation valve PVLA – To refill the circuit with oil in the luffing system this valve is used.

Shock and suction valve PVPL – Same as PVLA but also equipped with a shock valve.

Electric unloading valve PVPX – On the pump side module an electric unloading valve is mounted. This valve is not activated while idling, this provide a low pressure for idling. While driving the valve is activated by the electric control.

Tank side module PV – The main line to tank is connected to this module. It can also include a pressure reduction valve for the pilot pressure when the valve unit contains the electric activator.

Proportional valves PVG 32

proportionalvalvePVG32

Proportional valves PVG 120

proportionalvalvePVG120

 

This is the perfect place to share your knowledge and your skill about hydraulic schematics.

Handling proportional valves
Written by: PT.CALTAV INDONESIA
Reting: 4.6


PT.CALTAV INDONESIA is a company specialized in Hydraulic, Mechanical and Electrical system, HVAC, Servicing, overhaul and Commissioning for ship deck machineries and Ship deck crane, including Trading and other supplies for marine and offshore industries.


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