crankshaft
27 Feb , 2026
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RA Power Solutions was called by a leading shipping company based in Baku, Azerbaijan, regarding a major breakdown in their auxiliary engine, a MAK 6M20, installed on the vessel.
The vessel was stranded due to the non-operation of two auxiliary engines installed on board. Considering the urgency of the situation, RA Power Solutions deputed two technicians along with a specially designed onsite crankshaft grinding machine capable of grinding crankpins with small diameters and narrow widths.
In the case of the MAK 6M20 auxiliary engine, the standard diameter of the crankpin is only 152.00 mm, with a bearing width of 71 mm. The design of our onsite crankshaft grinding machine is such that it can be mounted on the crankpin diameter through the inspection window, and grinding is executed in situ.
The details of the engine are as follows:
| Engine details | ||
| S. No. | Crankpin Details | |
| 1 | Engine Make | MAK |
| 2 | Engine Model | 6M20 |
| 3 | Auxiliary Engine Number | #01 & #02 |
| 4 | Crankpin Diameter Standard | 152.00 MM |
| 5 | Crankpin Bearing Width | 71.00 MM |
| 6 | Grinding of Crankpin Number | #01, #02, #03, #04, #05, #06 |
| 7 | Place of Execution of Grinding of Crankpin | Baku, Azerbaijan |
| 8 | Name of Shipping Company | Reputed Company from Baku, Azerbaijan |
| 9 | Date Of Execution | 27th October to 29th November 2025 |
On arrival of our technicians on board the vessel, an initial inspection of all the crankpins was conducted. All six crankpins of the MAK 6M20 showed excessive ovality. A copy of the preliminary dimensional inspection report is pasted below.
| SIZE OF CR Pins Before Grinding of A/E 01 | |||||||||
| A | Aa | C | Cc | B | Bb | Min | STD | Ovality | |
| CR-1 | 151.72 | 151.95 | 151.73 | 151.78 | 151.74 | 151.84 | 151.72 | 152.00 | 0.28 MM |
| CR-2 | 151.73 | 151.92 | 151.72 | 151.88 | 151.74 | 151.81 | 151.72 | 152.00 | 0.28 MM |
| CR-3 | 151.74 | 151.85 | 151.73 | 151.84 | 151.73 | 151.82 | 151.73 | 152.00 | 0.27 MM |
| CR-4 | 151.73 | 151.93 | 151.74 | 151.85 | 151.75 | 151.89 | 151.73 | 152.00 | 0.27 MM |
| CR-5 | 151.71 | 151.85 | 151.69 | 151.80 | 151.71 | 151.78 | 151.69 | 152.00 | 0.31 MM |
| CR-6 | 151.76 | 151.93 | 151.73 | 151.87 | 151.74 | 151.85 | 151.73 | 152.00 | 0.27 MM |
All crankpins were ground by the technicians of RA Power Solutions, and the following dimensions were maintained.
| SIZE OF CR PINS AFTER GRINDING OF A/E 01 | |||||||||
| A | Aa | C | Cc | B | Bb | Min | Maxi | Ovality | |
| CR-1 | 151.00 | 150.99 | 150.99 | 150.98 | 150.99 | 151 | 150.98 | 151.00 | 0.02 MM |
| CR-2 | 150.99 | 150.98 | 150.97 | 150.98 | 150.99 | 150.98 | 150.97 | 150.99 | 0.02 MM |
| CR-3 | 150.99 | 150.98 | 150.98 | 150.97 | 150.98 | 150.99 | 150.97 | 150.99 | 0.02 MM |
| CR-4 | 150.99 | 150.98 | 150.98 | 150.97 | 150.98 | 150.99 | 150.97 | 150.99 | 0.02 MM |
| CR-5 | 150.99 | 150.98 | 150.97 | 150.97 | 150.98 | 150.99 | 150.97 | 150.99 | 0.02 MM |
| CR-6 | 151.00 | 150.99 | 150.98 | 150.98 | 150.99 | 151 | 150.98 | 151.00 | 0.02 MM |
All other parameters, including hardness, MPI, and deflection, were checked and found to be within acceptable limits. It was jointly decided to proceed with the grinding of all the crankpins, and they were machined by RA Power Solutions to a final size of 151.00 mm, i.e., 1.00 mm undersize as per the dimensions given above.
During the stay of our technicians on board the vessel, the crankshaft of Auxiliary Engine 02 was also inspected. Excessive ovality, showing the same pattern as that observed in the crankshaft of Auxiliary Engine 01, was detected. The preliminary dimensional inspection report is pasted below.
| SIZE OF CR Pins Before Grinding of A/E 02 | |||||||||
| A | Aa | C | Cc | B | Bb | Min | STD | Ovality | |
| CR-1 | 151.73 | 151.85 | 151.74 | 151.84 | 151.75 | 151.82 | 151.73 | 152.00 | 0.27 MM |
| CR-2 | 151.73 | 151.85 | 151.72 | 151.83 | 151.70 | 151.81 | 151.7 | 152.00 | 0.30 MM |
| CR-3 | 151.72 | 151.85 | 151.71 | 151.84 | 151.69 | 151.83 | 151.69 | 152.00 | 0.31 MM |
| CR-4 | 151.75 | 151.85 | 151.72 | 151.84 | 151.73 | 151.86 | 151.72 | 152.00 | 0.28 MM |
| CR-5 | 151.73 | 151.84 | 151.69 | 151.82 | 151.70 | 151.84 | 151.69 | 152.00 | 0.31 MM |
| CR-6 | 151.73 | 151.92 | 151.72 | 151.89 | 151.75 | 151.84 | 151.72 | 152.00 | 0.28 MM |
This crankshaft was also ground by our technicians, and the following dimensions were maintained. Both engines were successfully commissioned in the presence of our technicians.
| SIZE OF CR Pins After Grinding A/E 02 | |||||||||
| A | Aa | C | Cc | B | Bb | Min | Maxi | Ovality | |
| CR-1 | 151.00 | 150.99 | 150.99 | 150.98 | 150.99 | 151 | 150.98 | 151.00 | 0.02 MM |
| CR-2 | 151.00 | 150.99 | 150.99 | 150.98 | 151.00 | 150.98 | 150.98 | 151.00 | 0.02 MM |
| CR-3 | 151.00 | 150.99 | 150.98 | 150.98 | 150.99 | 151.00 | 150.98 | 151.00 | 0.02 MM |
| CR-4 | 151.00 | 150.99 | 150.98 | 150.99 | 150.99 | 151.00 | 150.98 | 151.00 | 0.02 MM |
| CR-5 | 151.00 | 150.99 | 150.98 | 150.98 | 150.99 | 151.00 | 150.98 | 151.00 | 0.02 MM |
| CR-6 | 151.00 | 150.99 | 150.98 | 150.98 | 150.99 | 151.00 | 150.98 | 151.00 | 0.02 MM |
RA Power Solutions offers onsite crankshaft grinding and repair services under a wide range of conditions, whether on a ship at sea or at a power plant/cement plant in a remote location. RA Power guarantees all crankshaft grinding services, ensuring the crankshaft and diesel engine perform satisfactorily after repairs.
For more information on onsite crankshaft repair, grinding of crankshaft, and crankshaft polishing, please email us at rajshahani@rapowersolutions.com, or info@rapowersolutions.com, or call us at +91 9582647131 or +91 9810012383.