REVERSING CYLINDER OVERHAUL
ATTENTION TO BE PAID FOR REVERSING CYLINDER OVERHAUL
In connection with the document subjected “REVERSING CYLINDER HEALTH CHECK” we would like to submit a supplementary document, which also will help to keep your reversing cylinders in good condition.
1. SUPPLY CORRECT SPARE PART TO VESSEL:
This problem occurs more than you expected...
Basically, there are 4 reversing cylinder suppliers, HAEWON-AVENTICS/REXROTH-NABTESCO and BOKYOUNG and None of their internal parts are identical for those brands to each other’s. Only the complete cylinder replaces the other, subject to proper installation.
The main reason for incorrect spare part supply can be explained with below example:
1.1.1. Let say your original reversing cylinders are Haewon…In the past, somebody supplied to the vessel 2 pieces of complete Aventics/Rexroth cylinder and those replaced by ship crew. Then during spare part order, you are asking to crew to send label of the reversing cylinders for correct supply. They are sending you a label, and you supply spare parts based on the label, but actually you have two different types of reversing cylinders on board.
Before ordering spare parts, all labels and shapes of cylinders should be checked carefully in order to prevent incorrect supply. We often encounter such problems during our service work.
2. DO NOT REMOVE COMPLETE CYLINDER DURING OVERHAUL:
Recently we have attended a troubleshoot where one of the cylinder does not able to change its position to astern, even though ship crew replaced complete reversing cylinder with new one.
We had found a loose connection between reversing cylinder shaft and reversing link during our inspection. Consequently, the clearances (A&B) between the guideway and pin of the reversing link were found to be out of the limit.
Our experiences show that, generally, ship crew like to remove complete air cylinder during overhaul. We do not recommend that method in order to keep A,B clearances within limits and avoid operational problems.
Instead, it should be overhauled, same as in
the below picture…Please refer to the below pictures for correct overhauling of
the cylinder. More simple, less risky…Just mark the reversing shaft and make
sure it is not turning while you lose shaft nut.
Threadlock to be used to fixing the nut between reversing shaft and piston shaft as specified in instruction manual.
If you the change correct clearence of A and B which can be found engine-specific instruction manual, you will face mechanical damages due to less clearence and oscilating of the reversing due to excessive clearence both will create problems for maneuvering.
3 TAKE IT EASY WHEN TIGHTENING:
Nuts&bolts to be tightened to specified torque…
4. KEEP SYSTEM WELL MAINTAINED:
Try to supply to system clean air and keep
the equipments well maintained.
Preventive actions always safe and
favourable than rectifying the problems…
