Marine diesel engine “Pneumatic Start Motor” Analysis

Pneumatic launch motor, due to its high starting torque, high reliability, low failure rate, strong adaptability, is widely used in a shipbuilding diesel engine of 3000kW. Whether it is a domestic machine or Japan, Europe’s diesel engine, although the pneumatic start motor used is different, but the principle is similar, here, the Model 45M AIR Starter used in Josco Suzhou Rottilan Deputy Machine Substitute as a sample, parsing Pneumatic starting motor work principle, pay attention, failure analysis, and management.

1. Working principle:

Under the premise of ensuring that the gas, the power is good, press the start button

The starting solenoid valve opens the control air. Under the action of control of air, the drive shaft is engaged with the diesel flywheel, and then control the air to further open the axial startup valve, so that the activation air enters the activation motor, drive the turbine high speed rotation, high-speed rotation turbine The action of the differential gearbox is rotated together to drive the drive shaft, so that the diesel engine is rotated to the specified speed, at this time, the solenoid valve is activated automatically, and the air is turned off, and the drive shaft is reset, and the motor is started.

Specific steps are as follows:

1 First action is the starting solenoid valve K (5 in the launch system diagram) in FIG.

2 and then control the air through the solenoid valve, enter the tray vehicle (7), if the disk passenger is disengaged, the air will reach the pre-meshing split after the drive machine (M) in Figure 4, then push The piston further drives the drive shaft N to engage the teeth on the diesel flywheel.


3 After the mesh is successful, the control of the air will continue to travel, and the start valve is opened by controlling the air line (c) in Fig. 1, and the startup valve is opened before the axial start valve (A) in Fig. 1.


4 Wait to start the air before start the valve, the nozzle (b) in Fig. 1 is reached by the starting valve (B) in Fig. 1, after the air flow of the nozzle, the air push turbine (e) in Fig. 2 is high-speed rotation, departure The air of the turbine is reached in the atmosphere by the treatment of the silencer (D) in Fig. 1.

5 At this time, the high-speed rotating turbine drives the active gear set (g) in Fig. 3 by the turbine shaft (f) in Fig. 2 to drive the driven gear set (Fig. 3). J) rotate together, but the speed is different.

6 The drive shaft (n in Fig. 4) is co-connected with the slave gear group, and also rotates at the same speed from the slave gear group, and the gear on the drive shaft is rotated together with the meshing flywheel, thereby driving the diesel rotation Get up, until the specified speed is reached, start the solenoid valve atmosphere, disconnect the air, while disclosing the air in the control line to the atmosphere, at this time, the drive shaft is disengaged with the flywheel under the action of the reset spring, while starting The motor stops rotating and the startup program ends.

2, pay attention to the point:

1 Control the air is to reach the tray first, only when the drive is normal from normal, the air will arrive.

2 The premise of starting the motor is to drive the axis to be engaged with the flywheel of the diesel engine. If the engagement is unsuccessful, the control air does not reach the main start valve, the main start valve does not open, the start motor cannot rotate.

3 The action of the differential gearbox is similar to the friction of the oil supply machine to quickly drive the side of the high-speed rotation to the side of the low-speed rotation, so that both sides are simultaneously rotated but the speed is different. However, excessive start-up air pressure can cause the turbine’s overspeed rotation, which causes the gearbox and the wear or damage to the associated gear, so that the pressure to activate the air is in a suitable range.

3, fault analysis:

(I) The starting motor and the flywheel do not engage, the drive shaft does not move.

According to the analysis of the above working principles, it can be found, mainly by investigating the following points;

1 No compressed air reaches the starting solenoid valve or low compressed air pressure

(Check if the air line related valve is opened, whether the air pressure is normal.)

2 starting the solenoid valve without action

(Dejure whether the solenoid valve is opened normally by comparing the air pressure of the air line before and after the solenoid valve.

3 disk passenger is not disengaged, or chain structure fault

(Check the pressure on the air line before and after the tray, if there is no air after the control of the air line, it is the disk chain, and the control air cannot be passed through the drive.

4 Pre-meshing piston and drive shaft failure.

(The air pressure before the pre-meshing piston is normal, but the drive shaft does not operate, and the control air line can be disassembled, and the vacuum is blown by the vacuum, and it is active. If it is still not action, it is a piston or drive. The axes and other cards can only be lubricated or cleaned.

(Ii) The motor does not rotate.

First determine whether it is normal to mesh normal, if there is no mesh, according to the analysis in (1), if it has been meshed with the flywheel, it can be investigated according to the following points;

1 start motor without any reaction

(First, determine if the control air line before starting the valve has compressed air, if the air is started, the air is normal, the motor is not reacted, the main start valve bar is blocked, no open, need to be demolished)


2 The airflow flows out from the muffler, but the flow is small.

(The start-up air pressure is too low, the main start valve opening is too small, or the silencer causing the air flow to reduce the launch torque. At this time, listen to the motor, to start the motor, can feel the turbine, but no Drive drive shaft.)

3 The sound of gas is very large, there is a large amount of air flowing from the muffler, but the motor drive shaft does not rotate.

(First check if the diesel is can’t rotate. If the diesel engine is normal, it may be that the launch motor nozzle is serious, lost the flow of the flow or the turbine, differential gearbox and related transmission component card resistance. At this time Listen carefully or feel, if the turbine is turning, but the drive shaft does not turn, it is the problem of the drive shaft or the differential gearbox driven gear set. If the turbine is not rotated, the turbine and differential gear are turbocyt. Problems on the side of the box active gear)

㈢ Start the motor speed very slow

1 The amount of air from the muffler is very small, the sound is small

(The main start valve is not fully opened, the silencer is dirty, or the air pressure is lacking)

2 The sound of gas is abnormal, but there is still a lot of air outflow from the muffler.

(Nozzle wear seriously or launch motor interior card resistance, turbine, differential gearbox and related transmission part card resistance failure)

4, daily management:

Due to the high reliability of the pneumatic start motor, the fault rate is low, many crew members are very familiar with it, but it is very strange to its internal structure and working principle, one but the problem is often busy. Therefore, it is recommended that the veneer of the pneumatic motor is equipped with a set of spare parts. In case of a failure, it can be replaced with confidence. (Recommended spare parts: start the solenoid valve, axial main start valve, pre-meshing piston correlation seal, transmission of the transmission mechanism)

When using daily use, pay attention to the quality of the compressed air, try to remove it, keep the air dry. Keep the appropriate start-up air pressure, if the pressure is too high, regulate the pressure reducing valve in time. At each time start, pay attention to listen to the sound of the motor, and find an abnormally check to avoid a more serious mechanical loss.

Original: Wu Xinchao