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Gearbox 120B Installation and Test Run

Jul 27, 2022 | Installation and Commissioning | 0 comments

Marine gearbox model 120B performs the duties of ahead and astern, engaging and disengaging as well as reduction of speed. It can be coupled with various diesels with applicable torque to form a complete power unit for marine purpose, which is suitable for all kinds of boats navigating in inland rivers or in coasts.
The astern transmission system can work under continuous and full-power conditions, therefore it can be matched with the diesel with same rotation direction to form the left-hand or right-hand power unit.

When using the gearbox, pay attention please to the items as follows:
1. When installation, both the concentricity and surface parallelism between the input coupling and the diesel flywheel (or other power output shaft of marine engine ) should be less than 0. 15mm, the concentricity and the porallelism between the output coupling and the propeller coupling less than 0.05mm and 0.06mm.
2. Only specified clean oil can be used.
3. During normal reversing, reduce the engine speed at 50% rated speed firstly, stay at “stop”position for 2~3 seconds and reverse, then speed up the engine again…
4. Under the conditions of the rated speed and the max. oil temperature, the oil pressure gauge should be regulated as follows:
(1) Working oil pressure is 1~1.2 MPa.
(2) Under the conditions of the rated speed and power, the lubricating oil pressure is within 0. 15~0.3MPa. ( When reversing at the speed of 300~500r.min-1,the pressure may reduce to 0.05~0.1MPa.) If the lub. oil pressure is too low, the clutch can’t disengage thoroughly, causing turning in company or burning-out on the frictional plates. If it is too high, the oil through the cooler is reduced, causing ascent of oil temperature.

Installation and Trial Running

1. When installing a new gearbox, it is necessary to remove the side cover for observing the internal parts and to make sure that the surfaces of the parts are rust-free. The input and output couplings should be ready to rotate freely by hand.

4. When remote control is needed, rotate the handle of control valve with steel wire or flexible shaft. Care should be taken when assembly that the working position of the valve is correct.

3. Both gearbox and engine should be placed on a common base and fastened by reamer bolts. To keep assembly accuracy ( Refer to “FOREWORD”) and carry out regular inspection during operation.

  1. The cooling water supplied for the cooler should not be less than 2n3/h, which should pass through the cooler first, then to that of diesel engine or to be directly drained out.

5. After the installation, fill in clean oil up to the specified level and start the engine at 50% rated speed. Observe the reading of the oil pressure gauges. If there is no reading on the gauges within one minute after starting, stop the gearbox for inspection and shoot the trouble because running without sufficient oil is not permissible. When the oil pressure is formed, speed up the engine gradually to the rated speed and regulate the working oil pressure and lub. oil pressure to the specified value. The gearbox is to be continuously run for 5~10 minutes, reversed for two or three times, inspected whether any abnomal noise or any leakage of oil or water occurs.

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