MTZ 1220.1/1220.3 Section D. Construction and Operation
D31
.
Air intake into the pneumatic drive
is made through the engine inlet duct. Air
is compressed in the compressor (1) and,
then, fed to the air bottle (4) via a pressure
regulator (2). The latter helps to maintain
the required pressure in the bottle. Com-
pressed air is supplied from the air bottle
to the brake valve (13) and into the feed
duct (12) with a coupling head (a red lid)
which is permanently under pressure. The
brake valve (13) is connected with the
coupling head (10a) (with yellow lid)
through the control duct (11). There is no
pressure in this head.
The trailers’ and farm machinery
brakes are controlled in two modes: direct
and automatic.
In case of use of the trailer with
double-line pneumatic actuator, the cou-
pling heads of the trailer are connected to
those (10) (with a red lid) and (10) (with a
yellow lid), i.e. to the feed duct (12) and to
the control duct (11). Here compressed air
is fed continuously to the trailer through
the fed duct (12). On stepping the brake
pedals or applying the parking brake,
compressed air is delivered to the trailer
through the brake valve (13) and control
duct (11). The air distributor on the trailer
operates to feed the compressed air from
the trailer bottle into the brake chambers
that causes the braking of the trailer.
The direct brake control is
achieved through the pressure increase in
the control duct (11) up to 6.5…8.0
kgf/cm
2
when braking the tractor. As this
takes place, the feed duct (12) remains
under pressure, and compressed air sup-
ply to the trailer’s pneumatic system is still
retained.
The automatic brake control
(automatic braking) is effected due to a
pressure drop in the trailer feed duct in
case of rupture of the coupling and de-
tachment of the trailer.
The coupling ducts are fitted with
coupling valve-type heads (10) at their
ends. The valve of the coupling heads
prevents the exit of air when the pneu-
matic drive is used with no trailer attached
(for example, when inflating tyres) and in
case of emergence detachment of the
trailer. On coupling the duct of the tractor
with that of the trailer, the coupling head
valve opens to ensure the passage of
compressed air from the tractor’s pneu-
matic drive to the trailer. The connecting
ducts should be couple together at zero
pressure in the tractor air bottle (4).
The air pressure in the bottle (4) is
monitored by the air pressure indicator (6)
and red indicator lamp of air emergency
pressure (5) (installed in the dashboard),
air pressure sensors (7) and air emer-
gence pressure sensor (8).
The air bottle (4) is provided with
the cock (9) for draining condensate. To
drain condensate move the pusher ring
aside and upwards.
The air intake from the pneumatic
actuator (for inflating the tyres, etc.) is per-
formed through the air bleeder valve (3) of
the pressure regulator (2).
To Next Page
