Thursday, 10 December 2015
Reason for failures of paints?
1. Not proper cleaning of body before painting
2. Not covering dents or spots
3. Not using of proper good quality paint
4. Not applied the pretreatment with zinc phosphate
Requirements of Good Painting?
2. It should protect the hidden parts also from the corrosion.
3. It should have esthetic appearance.
4. It should be smooth finish for stream lining.
5. It must reduce the aerodynamic drag.
Automotive Painting
The corrosive nature of a metal used in a motor body
construction, necessitate the application of an anti corrosion coating. For this
reason the painting should be done.
Function of Painting:
1. It reduces the corrosion and protect the vehicle
body.
2. It is used for cleanliness.
3. It is used for esthetic appearance.
4. It is used to reduce the friction due to the
aerodynamic drag and allow the vehicle in stream
lining.
5. It is used for identification purpose.
Tuesday, 1 December 2015
Different methods to door lock or unlock mechanisms?
1. With a key
2. By pressing the unlock button inside the car
3. By using the combination lock on the outside of the door
4. By pulling up the knob on the inside of the door.
5. With a keyless – entry remote control.
6. By a signal from a control center.
Torsion Bar in suspension system?
Torsion Bar
Torsion bar suspension is used in independent suspension system. It is a
rod acting in torsion and taking shear stresses only. It is made up of heat
treated alloy spring steel. This bar stores amount of energy nearly as same as
coil spring.
The bar is fixed at one end to the fr4ame, while the other end is fixed to
the end of the wheel arm and supported in the bearing. The other end of the
wheel arm connected to the wheel hub. When the wheel strikes a bump, it
starts vibrating up and down, thus exerting torque on the torsion bar which
acts as a spring.
Stabilizer Bar in suspension system?
Stabilizer is necessarily used in all independent front suspension. It
reduces tendency of the vehicle to roll on either side when taking a turn. It is
simply a bar of alloy steel with arms at each end connected to the lower wish
bone of the independent suspension system. It is supported in bush bearings
fixed the frame and is parallel to cross member. When both the wheels
deflect up or down by the same amount, the stabilizer bar simple turns in the
bearings. When only one wheel deflects, then only one end of the stabilizermoves, thus it acts as a spring between two sides of the independent front
suspension.
Working of Single acting Telescopic hydraulic shock absorbers?
If the axle eye moves upwards then the fluid must be displaced
from the bottom. Top side of the bottom side fluid through the outer ring of
the piston by lifting the non return valve. But since the increase in the volume
of upper end of the cylinder is less than the volume of the lower end. Fluid will
also displaced through the inner ring of holes of non return valve of foot
valve, and the level at the fluid will raise in the reservoir. The pressure setup will
depend on the size of hole in the piston and Foot valve and the squire of the
speed of which the cylinder is moved.
For downward motion of the cylinder the fluid will be displaced form
the upper end of the piston. In the leaver end through the inner ring of hole of
non return valve in the piston. The fluid will also be draw in the lower end of
the cylinder from the reservoir to the outer ring of hole of non return valve of
the foot valve.
Fig of shock absorber
Types of Shock Absorbers?
Types of Shock Absorbers:
They are mainly two types
1. Mechanical.
2. Hydraulic – a. Van type
b. Piston – i )Single Acting
ii). Double Acting
c. Telescopic type
Need of Shock Absorber?
If the suspension springs are rigid enough, they will
not absorb road shocks efficiently, and if they are flexible enough, they will
continue to vibrate for longer time even after the bump has passed.
Therefore, the springing device must be compromise flexibility and stiffness a
shock absorber needed in Automobile Suspension system.
Helper Springs?
The helper springs are used in heavy vehicles for rear suspension. When
vehicle fully loaded the main spring as well as helper spring to come in
action and absorb the road shocks. When the load of the vehicle is less the
helper spring will not act and the main spring only absorb the road shocks.
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