MTZ 952.2 - 2.2. Electric torch pre-heater (ETPH).; 2.3. Pre-start pre-heating glow plugs

Appendix
MTZ series 900
257
2.2. Electric torch pre-heater (ETPH).
The ETPH control system (А2) has the
following peculiarities (see Fig. 3):
1. The ETPH coil is powered up by the key
switch (SA12) located on the
instrumentation dashboard.
2. The additional resistor R1 if connected
serially into the coil circuit.
3. When closing the contacts "30" and "87",
the ETPH relay (K8) shunts the additional
resistor. The relay winding is connected
into the circuit in parallel to the starter
solenoid switch (K7) and operates with in
the same mode with the latter.
4. Simultaneously with warming up the
ETPH coil, the test lamp in the pilot lamp
block HG2 on the instrumentation
dashboard.
5. When the pilot lamp operation will be
changed from the steady lighting to the
blinking, start the engine. On switching on
the starter, the current from the terminals
"СТ" of the starter switch (SA6) is passed
through the second pair of contacts of the
switch (SA15) to the electric torch pre-
heater solenoid valve, which operates, the
fuel is fed to the suction manifold and
ignited by the preheated coil of the electric-
torch pre-heater. At the same time, the
contacts of the electric torch pre-heater
relay contacts (K8) are closed and the
additional resistor is excluded from the
circuit that compensates to compensate for
the voltage at the electric torch pre-heater
coil having occurred due to switching on
the starter.
After starting the engine, the starter and
relay are de-energized automatically. The
additional resistor in connected into the
electric-torch pre-heater coil again to
protect the same against fusing due to the
voltage increase after beginning of the
operation of the alternator.
To allow the engine to reach the stable
working mode, the work of the electric-torch
pre-heater s possible after automatic
switching-off of the starter at the cost of
continuing to keep the switch SA15 on the
on state and of the starter switch in the “II"
position.
2.3. Pre-start pre-heating glow plugs
The glow plugs А2 (see Fig. 4) used as
starting aids for the turbocharged engines
certified according o the European
ecological norms (Euro-2).
The control scheme for the glow plugs А2
has the following peculiarities:
1. The glow plugs are energized by turning
the key of the starter switch SA6 to the “І”
position.
2. The circuit for control of the glow plugs
includes the starting-aid pilot lamp , relay
glow plug (K1) and glow plug block (glow
plug control module) (KТ1). Here the relay
(K1) is a power relay and the unit (KТ1)
performs the functions of control of the
power relay while tracing the integrity of the
circuitry of the glows (А2).