12 - 3
Operation (cont'd)
The high temperature, high pressure refrigerant is forced by
compressor action into the expansion valve
4
, which meters
the amount of refrigerant entering the evaporator. In the
expansion valve the refrigerant instantaneously expands to
become a low pressure, low temperature liquid.
The refrigerant is drawn through the evaporator coil
5
by the
suction of the compressor. The temperature of refrigerant is
now considerably below that of the air being drawn across
the evaporator coil by the blowers. Heat is transferred from
the ambient and recirculated air to the refrigerant, causing
the low pressure liquid to vaporise and become a low
pressure gas. Moisture in the air condenses on the
evaporator coil and is drained away via condensate.
Cool de-humidified air is emitted through air vents into the
cab.
The low temperature, low pressure, high heat content
refrigerant gas, is now drawn by suction back to the
compressor, where the cycle is completed.
Control
Control of the system is achieved by the cyclic action of the
compressor's electromagnetic clutch. When current is fed to
the field coil of the compressor's clutch, a magnetic field
develops between the field coil and the armature which pulls
the field coil, complete with clutch assembly, onto the
compressor's rotor. Since the clutch assembly is turned
constantly by the crankshaft pulley drive belt, the
compressor armature turns, starting the refrigeration cycle.
Current is fed to the field coil through three series switches
whose contacts are controlled by the following:
1
The manual switch
D
in the cab
2
The thermostat switch monitoring the evaporator
temperature
3
The high and low level pressure switch
Switch
D
will start the refrigeration cycle provided that the
ambient temperature in the cab is greater than 0°C and the
refrigerant pressure remains within the specified limits.
The thermostat has its sensor inserted in the evaporator coil.
It controls the refrigeration cycle by switching the
compressor clutch on and off to prevent freezing of the
condensate on the evaporator coil.
The pressure level switch is housed in a common assembly
located on the Receiver Drier. If the refrigerant pressure
exceeds the upper pressure limit specified or falls below the
lower limit, the contacts will open and the clutch will
disengage, closing down the refrigeration cycle.
Pressures Switch Settings
High Pressure Switch 28 bar (406 lbf/ in
2
)
Low Pressure Switch 2.1 bar (30.4 lbf/ in
2
)
Safety Procedures
The air conditioning system includes a pressurised closed
circuit containing a non-CFC, environmentally friendly
refrigerant, Type R-134a. Any service procedure which
breaks into the closed circuit and therefore requires
discharging of the system, must only be carried out by
service personnel with specialist knowledge of air
conditioning systems. The following guidelines should be
adhered to by all personnel servicing the air conditioning
system.
!
!
WARNING
The air conditioning system is a closed loop system and
contains pressurised refrigerant. No part of the system
should be disconnected until the system has been
discharged by a refrigeration engineer. or a suitable
trained person You can be severely frostbitten or injured
by escaping refrigerant
4-3-4-1/2
!
!
CAUTION
Do not operate the air conditioning system when there is
no refrigerant in the system, otherwise the compressor
will be damaged.
4-3-4-4
1
It is critical that the correct refrigerant (R-134a) is used
and that charging is done only by qualified personnel.
As a precaution, in case of accidental leakage,
discharging and charging of the vehicle refrigerant
system must be conducted in a well ventilated area.
2
Containers of refrigerant should be stored in a cool
environment away from direct sunlight.
!
!
WARNING
Do not carry out welding operations close to the air
conditioning refrigerant circuit. A poisonous gas is
produced when refrigerant comes into contact with
naked flames. Do not smoke or allow naked flames close
to the refrigerant circuit.
BF 1- 9
3
Do Not
perform welding operations close to refrigerant
hoses (maintain a distance of at least 0.5m from hoses).
4
Do Not
steam clean refrigerant system components.
5
When charging or discharging the refrigerant system
refrain from smoking. Naked flames must not be
allowed in the immediate vicinity. The refrigerant does
not give off a poisonous odour, however, when it
comes into contact with a naked flame, a poisonous
gas is produced.
6
When handling refrigerant, rubber gloves and goggles
should be worn. Operators should ensure that no
refrigerant comes into contact with the skin. Particular
care should be taken when connecting or
disconnecting charging hoses or pressure switches.
When these components are connected to the system,
a short release of refrigerant occurs. This results in a
high velocity, very cold gas being emitted from the
connection point.
Section B
Body & Framework
9803/6410
Section B
12 - 3
Issue 1
Air Conditioning
Содержание JS130
Страница 39: ...3 3 Section 3 Routine Maintenance 9803 6410 Section 3 3 3 Issue 1 Greasing continued Excavator End...
Страница 65: ...Section 3 Section 3 9803 6410 Issue 1 9 1 9 1 Routine Maintenance Component Location Diagram...
Страница 118: ......
Страница 119: ...3 1 Section C Electrics 9803 6410 Section C 3 1 Issue 1 Layout Operator s Cab...
Страница 142: ...5 3 Section C Electrics 9803 6410 Section C 5 3 Issue 1 Pump Control FLOW CHART...
Страница 145: ...5 6 Section C Electrics 9803 6410 Section C 5 6 Issue 1 Pump Control Cushioned Boom Starting continued Flow Chart...
Страница 148: ...5 9 Section C Electrics 9803 6410 Section C 5 9 Issue 1 Pump Control Pressure Increasing System continued Flow Chart...
Страница 155: ...5 16 Section C Electrics 9803 6410 Section C 5 16 Issue 1 Pump Control Power Supply Cut Delay Flow Chart...
Страница 159: ...5 20 Section C Electrics 9803 6410 Section C 5 20 Issue 1 Pump Control Swing brake Swing lock continued Flow Chart...
Страница 160: ...5 21 Section C Electrics 9803 6410 Section C 5 21 Issue 1 Pump Control Lever Lock Circuit Diagram Time Chart...
Страница 161: ...5 22 Section C Electrics 9803 6410 Section C 5 22 Issue 1 Pump Control Lever Lock continued Flow Chart...
Страница 207: ......
Страница 209: ......
Страница 210: ...3 4 Section E Hydraulics 9803 6410 Section E 3 4 Issue 2 Schematics Shuttle Block...
Страница 211: ...Section E Section E Hydraulics 9803 6410 Issue 2 3 5 3 5 Schematics Pilot Control Line Hose Connection Diagram JS03540...
Страница 212: ...Section E Section E Hydraulics 9803 6410 Issue 1 3 6 3 6 Schematics Pilot Control Line Hose Connection Diagram JS03540...
Страница 234: ...14 1 Section E Hydraulics 9803 6410 Section E 14 1 Issue 1 JS00010 Hydraulic Pump Regulator Dismantling and Assembly...
Страница 278: ...32 2 Hydraulic Circuit Diagram Section E Hydraulics 9803 6410 Section E 32 2 Issue 1 Control Valve JS01700...
Страница 279: ...33 1 Neutral Circuit Section E Hydraulics 9803 6410 Section E 33 1 Issue 1 Control Valve JS01610...
Страница 284: ...33 6 Boom Raise BM Operation Section E Hydraulics 9803 6410 Section E 33 6 Issue 1 Control Valve L...
Страница 287: ...33 9 Slew Operation SW Priority Circuit Section E Hydraulics 9803 6410 Section E 33 9 Issue 1 Control Valve JS01770...
Страница 293: ...Hydraulics 9803 6410 Issue 1 34 3 34 3 Section E Section E Control Valve JS01820 Dismantling and Assembly cont d...
Страница 532: ...Contents Page No Technical Data 1 1 i Engine 9803 6410 i Issue 1 Section K Section K...