8.7. System of decrease in toxicity at sharp closing of a butterfly valve

This system provides smooth closing of a butterfly valve at sharp braking with the engine owing to what the fuel which was not in time to burn down does not get to the fulfilled gases and does not lead to increase in environmental pollution.
The system consists of the valve of a flame arrester and the pneumatic shock-absorber installed on the carburetor (on models with the mechanical transmission), the managing director of a butterfly valve.
Sign of malfunction of the pneumatic valve is immediate closing of a butterfly valve at a sharp otpuskaniye of a pedal of an accelerator. The refusal of a flame arrester can be shown in the form of the return emissions of a flame of the burning-down mix and in further work of the engine after switching off of ignition.

Check of technical condition 
Flame arrester

Fig. 8.5. Valve check of a flame arrester


Launch the engine and bring a hand from above to a flame arrester (fig. 8.5).
Increase the frequency of rotation of a bent shaft of the engine up to 3000 min.-1, then quickly release a butterfly valve. The flame arrester works normally if from it the air stream is felt.
Transfer the engine to the idling mode. Disconnect an air hose from a flame arrester and close an entrance opening of a hose. If the frequency of rotation of a bent shaft of the engine idling after a detachment of an air hose strongly differs from rotation frequency to a detachment, so leak appeared – the flame arrester should be replaced.
Pneumatic shock-absorber
Sharply take away the lever of a butterfly valve from the pneumatic shock-absorber and check the speed of movement of a rod of the pneumatic shock-absorber for all its length. Release the lever of a butterfly valve and be convinced that after contact with a rod of the pneumatic shock-absorber the lever smoothly comes back to the situation corresponding to idling.
To adjust the pneumatic shock-absorber, launch the engine, warm up and leave to idle.
Connect a tachometer. Slowly increasing the frequency of rotation of a bent shaft of the engine, check whether the rod of the pneumatic shock-absorber departs from the lever of a butterfly valve approximately at 2200 min.-1. For adjustment release a lock-nut and tighten the pneumatic shock-absorber.
If after adjustment the pneumatic shock-absorber does not work in the set mode, replace it.

Replacement of details
Flame arrester
Remove the airbringing hose and, having wrung out latches, disconnect a flame arrester from an arm.
Establish a new flame arrester in an arm and connect the airbringing hose.
Pneumatic shock-absorber

Fig. 8.6. The pneumatic shock-absorber with elements of fastening and the drive


Weaken a lock-nut and turn out the pneumatic shock-absorber from an arm (fig. 8.6).
Install the new pneumatic shock-absorber and adjust it as it is described above.