Specifications

Service Training
Section 4.9
Page 34
12.05
4.9.3.2 FUNCTIONAL DESCRIPTION OF THE PROPELLANT GAS SYSTEM
The various stages of the gas system are described below with their operating positions:
OFF POSITION
- Ignition start switch (11) open.
- Electromagnetic shutoff valve (12) in open position.
- Vacuum-controlled shutoff valve (14) closed.
- Throttle valve in mixer (3) closed.
ON POSITION
- Ignition start switch (11) closed.
- Electromagnetic shutoff valve (12) in closed position.
- Vacuum-controlled shutoff valve (14) in closed position.
- Throttle valve in propellant gas mixer (3) open.
START
During the starting process, the vacuum moves from the intake manifold (2) via the open throttle valve of
the mixer (3) and the conduct (4) to the vacuum-controlled shutoff valve (14) and activates a diaphragm.
This opens the shutoff valve and allows LP gas to flow through the conduit (10) to the primary valve in the
vaporisor (9).
A vacuum also passes through conduit (6) in the secondary stage of the vaporisor (9) and activates the
secondary valve via a diaphragm. Now depressurised gas flows through the open valve in gaseous form
through the conduit (6) to the mixer, where it is mixed with the air and led as an ignitable mixture through
the intake manifold (2) to the individual cylinders.
OPERATION
In operation, the position of the throttle valve changes through [the action of] the speed regulator, depending
on the speed and load of the engine. The resulting increase or reduction of the vacuum controls the
secondary diaphragm, via the conduit (6) from the mixer (3) to the vaporisor (9), and thereby the secondary
valve, this vacuum then changes the gas flow and the proportions of the mixture in the mixer (3).
If the vacuum is increased because of a dirty air filter, this pressure will, through the conduct (7), oppose
the opening pressure of the secondary diaphragm in the vaporisor (9). As a result the secondary valve in
the vaporisor (9) will partially close, the gas flow will be reduced and an excess density of gas in the mixture
will be prevented.