Transcript PowerPoint 演示文稿

BMC
Training Presentation
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UNDERCARRIAGE SYSTEM
 Component Assembly
 Operation Principles
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Bulldozer Assembly
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Power Take-off
Torque Converter
Universal Joint
Transmission Unit
Main Drive
Steering Clutch
Steering Brake
Final Drive
Track Equipment
Control System
Working Equipment
Cabin
Floor & Fender
Track Frame
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Power Train
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Engine
Torque Converter
Universal Joint
Gear Box
Main Drive
Steering Clutch
Final Drive
Track System
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Power Take-off
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Function:
PTO power
Equipment:
Work system pump
Transmission pump
Steering Pump
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Torque Converter Assembly
BMC
• Type:
3-element
1 stage
1 phase
• Assembly: Pump,
Turbine and Stator
• There are many
vanes on these
components for
using oil to transfer
power
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• These 3 components
combined with oil, give
us as smooth power
transmission.
• Safety valve: fitted to oil
input, ensures the input
oil pressure is no more
than 0.87MPa.
• Relief Valve: fitted on oil
output, ensures the oil
pressure inside the
torque converter is
maintained below
0.45MPa.
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Principles of Torque Converter
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• Oil Flow: Pump→ Turbine
→ Stator→ pump
• There is 2 mm clearance
between pump and
Turbine, and transfers
power by Oil. There is no
mechanical impact, they
protect each other
• Assist hydraulic system: to
resist loss of oil; to
maintain the normal oil
temperature.
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Operation of Torque Converter
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• When the load increases,
the dozer ground speed
is reduced, causing
turbine speed to slow
down. But at this time the
energy from the pump
transfer to torque
converter is not reduced.
This energy is still
transferring to the stator
through the slowing
turbine. Then the energy
to stator from turbine,
results in the turbine
gaining torque, then the
turbine output torque is
increasing.
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Torque Converter Operation
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1.Change torque
automatically
2.Absorb vibration,
prolong working life
3.Good power
transmission capability,
driving at slow speed
4.Simple operation
5. Start smoothly,
eliminates any shocks
in power train
6.Easy maintenance
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High Torque Converter Oil Temperature
Normally, SD22 Torque Converter Temperature of
output oil is 115-120oC. For a short time, a higher
temperature of 130-135oC is allowed, but long term
high temperature shows there is something wrong,
for the following reasons:
1.Shortage of Oil
Torque converter, transmission, main drive, steering
and final drive will take 30% of engine rated power.
This power will transfer to heat energy, and increase
the oil temperature. Therefore it requires enough oil
to absorb this heat.
If the oil quantity is not sufficient, the oil temperature
will be too high.
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2.Oil Pressure of input and output are incorrect
If torque converter input oil pressure is not correct
(Standard: 0.87MPa) or the oil is dirty, the piston of
valve will stay at relief position, so the oil pressure to
the torque converter is low. This leads to a loss of
efficiency and excessive oil temperature.
If torque converter output oil pressure is not correct
(Standard: 0.45MPa) or the oil supply is blocked,
return oil temperature will be too high. The flow of oil
to oil cooler is reduced, and the oil temperature too
high
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3. Incorrect Operation
Excessive use of low engine speed for extended
time, torque converter will work at low efficiency.
Torque converter will lose power, and transfer heat
energy leading to high oil temperature.
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Power Transmission Case
BMC
• The types of Transmission Case:
Base Operation type:
1.Manual Gearshift；2.Hydraulic booster；3.Powershift
Base Transmission type:
1.mechanical type; 2.Planetary Gear
• Planetary type powershift transmission case type:
Planetary Gear, Multi-disc clutch, Hydraulic control,
forced lubrication.
• Function:
1.Enable forward and reverse
2.Select different gear ratio
3.Matched with the torque converter, enables a wide
range of power output and ground speed
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Planetary Gear System
BMC
C
The system consists of:
A: Sun Gear
B: Planetary Gears
C: Ring Gear
D: Carrier
D
A
B
The planetary gears are
installed on the carrier being
in constant mesh with the
sun gear and the ring gear
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Planetary Gear system
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Principle of Planetary Gear system
If the carrier is fixed, the
torque is transmitted from
sun gear to planetary gear,
and is transmitted from
planetary gear to ring
gear to make the ring
gear rotate. Rotation
direction of ring gear is
opposite from sun gear.
A: Sun Gear
B: Planetary Gear
C: Ring Gear
D: Carrier
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Principle of Planetary Gear system
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If the ring gear is fixed, the
torque is transmitted from
sun gear to planetary gear.
The planetary gear rotates
by itself, at the same time
rotates around sun gear.
Rotation direction of the
planetary gear shaft is
opposite from sun gear.
It is a slowdown outfit that
power input from sun gear,
output from carrier
A: Sun Gear
B: Planetary Gear
C: Ring Gear
D: Carrier
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The above principles are structure principle of No.1,3,4
planetary gear system.
The sun gear is active in No.1 Planetary Gear system
The carrier is active in No.3 & 4 Planetary Gear system
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This is structure
and principle of
No.2 planetary
gear system.
The rotate
direction is
contrary with No.1
planetary gear
system.
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SD22 powershift transmission system
Consists of 4 planetary gear systems with 4 clutches,
and 1 locking clutch (no planetary gear system) and
housing, input shaft, end gear and output bevel gear.
No.1 clutch is for Forward Gear
No.2 clutch is for Reverse Gear
No.3 clutch is for 3rd Gear Shift
No.4 clutch is for 2nd Gear Shift
No.5 lock clutch is for 1st Gear Shift
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SD22 powershift transmission
system
The 4 planetary gear system clutch’s washers and disc are the
same, but the disc quantity is different. Its design is based on
transmission torque.
The No. of Clutch
No.1
No.2
No.3
No.4
No.5
Washer Q’ty
3
2
1
1
2
Disc Q’ty
4
3
2
2
3
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No.1- 4 planetary gear systems’
structure are same, clutches’
washer and disc are same,
but the disc quantity and
piston is different.
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Method of fixing of each planetary
gear is as this figure, it is actuated
by the clutch.
Engagement of clutch is actuated
by oil pressure from control valve
pushing piston 3.
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Disengagement of clutch is
actuated by return spring 33
which pushes piston 3 to
original position after oil
pressure is cut off.
The function of disc spring 42 is
to improve operating speed of
piston 3 and improve release
the discs.
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This figure is a drawing of No.5
locking clutch. When the clutch
disengages, oil in the cylinder
body 16 by the action of
centrifugal force. Disks can’t
disengage quickly, only by disk
spring 29. This can make the
clutch half disengage. This will
cause difficulty for next gearshift.
In order to eliminate this problem,
the ball check valve 17 is
incorporated in the piston after
the rotary clutch.
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No.5 Clutch is a lock
clutch.
When this clutch engages,
pressure oil from
controlling valve enters
into oil cavity and pushes
piston 26, at the same time,
the oil pushes check valve
ball 17 to plug the hole of
valve. The clutch is
engaged quickly.
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No.5 Clutch is a lock
clutch.
When the pressure oil from
controlling valve is cut off,
by the action of centrifugal
force, ball 17 can move to
the direction of arrow in this
figure. At this time, the hole
of valve cage is opened
and the oil is drained off.
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Forward 1st Speed
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Forward 2nd
Speed
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Forward 3rd
Speed
BMC
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Transmission Lubrication and
Cooling:
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It’s a forced lubrication system, from
above and below, two ways divided
through a valve.
Transmission Case lubrication pressure
is 0.124Mpa. Upper way lubricates the
second half bearing and cools the
second half discs; lower way
lubricates the first half bearing and
cools first half discs.
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Main Drive (SD22)
• Assembly:
Bevel gears
Horizontal Shaft
Bearings
Sprocket Hub
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• Functions:
Power train gear
reduction to
increase the final
drive torque
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Steering Clutch
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• Function:
To disengage the shaft
drive and control
steering
• Type:
Wet, multi-disc, spring
loaded, hydraulic
separated, normally
engaged.
• Spring force
F=3.2 tons
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Steering Clutch Operation
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Steering Brake
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• Function:
The brake on the
outside of steering
clutch’s outside drum,
reduced the rpm of the
final drive on that side.
• Type:
Wet band, hydraulic
boosted control
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Steering Brake Operation
Forward
BMC
Reverse
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Steering Brake Control
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Linkage through valves
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Steering Case Lubrication and
Breather
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• There are 3 associated components, Main drive,
Steering Clutch and Steering Brake. They are
lubricated and cooled by the oil in steering case.
The oil level can be checked with oil dipstick
• Steering case has a breather to balance inside
and outside pressures.
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Final Drive
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• Final Drive: One Set
Final Drive on each
side.
• 2 stage spur gears
reduction. Floating
Seal and O-ring to
contain oil, then
connected outside
with breather.
• Assembling
Sprocket hub and
gear requires 60
tons force with
special tools.
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Track System --- Walking Gear
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• Assembly:
Track Frames
Track Rollers
Carrier Rollers
Recoil system
Track Shoes
Equalizer
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Recoil system for Track
BMC
• Function:
1. Maintain track
tension
2 absorb the
vibration of idler
• Note:
the fixed
pressure is 20.38
tons, it requires
special fitting
tools
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Measurement of Track Tension
BMC
use a ruler placed on
the track grousers
between carrier roller
and idler, the measure
distance is C，C=2030mm
SD32 track has more
wide, the distance is
bigger between carrier
roller and idler, the
measured distance is
C=30-40mm
Idler
Carrier roller
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Idler
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• Function:
Gives guidance for
track chain and
maintains track tension
• Lubrication
There are lub oil in the
cage that is sealed by
floating seal, between
idler and support
housing. The oil
capacity is 70%.
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To Adjust Idler Clearance
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• If the clearance is over limit ,
the idler will swing, and track
links off centre and will wear
the sprocket.
• If Clearance in one side
A＞4mm,
it must be adjusted into
A=0.5-1mm
• If Clearance of up and down
(B+C)≥5mm
it must be adjusted into
(B+C)=2mm。
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Track Roller
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• First it carries dozer
weight, secondly it
prevent track chain
moving off centre of
track frame
• Bushing and float
seal is similar to idler
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Track Shoe
Assembly
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• Supports all of the
dozer weight, and
determines the
ground pressure
• Four high strength
bolts fix track shoe
onto track link,
bolt torque:
SD16:70kg.m
SD22:76kg.m
SD32:100kg.m
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Use and Maintenance of Track Shoe
Track supports 30 tons bulldozer weight, and if the working
conditions are bad, it will wear more quickly, so use and
maintain it correctly.
1. Often check the tension of track shoe. use a ruler put the track
grousers between carrier roller and idler, the measure is C，
C=20-30mm; SD32 track is more weight, the distance is more
large between carrier roller and idler, the measure is C=3040mm
When the work is hard, the track shoe ass’y will need to be
adjust tighter; if the work is moderate , the track shoe ass’y
tension can be adjusted back.
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Use and Maintenance of Track Shoe
2. The sprocket segments need be replaced when the sprocket
segments wear under the limit.
3. Don’t drive dozer hard and avoid track damage and excessive wear.
4. If there is excessive track play and noise, you must stop and check
tracks and machine.
5. When the dozer across the railway line, you must drive it across the
railway at right angle, and don’t change speed, don’t stop and
reverse, avoid track shoes locking in railway line.
7. After working, you must check tracks, and if there is something
wrong. If there is something wrong, must repair or replace.
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End of this Training Module
Thanks Your Cooperation !!!
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