OCTOBER 19-20, 2012 - YMCA University of Science & Technology

Proceedings of the National Conference on
Trends and Advances in Mechanical Engineering,
YMCA University of Science & Technology, Faridabad, Haryana, Oct 19-20, 2012
2.5 Causes due to Material
Cause: Bad Brake hose material
Counter measure:During vacuuming, if brake hose material has defect like crack or hole it causes leakage of
vacuum pressure, this results in pre-vacuum error. Due to defective brake hose material it also causes inflate of
brake hose at higher pressure. When brake pedal applied this causes expansion of brake hose and results in
accumulation of brake fluid inside the brake hose. Due to accumulation of brake fluid it damages the brake hose
resulting crack on brake hose, this leads to leakage of brake fluid.
Calculation for determining maximum pressure developed in brake system
Considering maximum Mass applied on brake pedal = 100 Kg
F d = Mass applied on brake pedal x Acceleration
F d = 100 x 9.80665 = 980.66 Kg-m/s 2 = 980.66 N
Approximating braking force (F d ) to 1000 N
F bp = (F d )x(L 2 ) / L 1 = (1000)x(435)/142 = 1000 x 3.0634
F bp = 3063.4 N
D MC = 25.4 mm
A MC = (π/4) x (D MC ) 2 = (π/4) x (25.4) 2 = 506.7075 mm 2
P MC =F bp /A MC = (3063.4)/(506.7075) = 6.0457 N/mm 2
By the Pascal law, fluid pressure remains same
P MC =Pcal=Pwc= 6.0457 N/mm 2
The maximum pressure developed in the Brake system is 6.0457 N/mm 2
Counter measure: Brake hose should have to with stand and do not inflate at pressure 6.0457 N/mm 2 .
3. Conclusion
A comprehensive root cause analysis using 5 - Why methodology to find the causes and reasons for brake
spongy defect resulted in identifing suitable counter measures for this problem.Out of 20 suspected causes for
brake spongy defect 11 causes are identified as potential sources of this problem. The list of these 11 caurces and
corresponding counter measures is given below.
(i) Tightening defect: Torque range for tightening brake tube is standardized and worker is employed to check
whether the torque for tightening different component is achieved.
(ii) More clearance between Brake pad and Rotor: This clearance is to be ≤ 0.3066 mm.
(iii) More clearance between Brake shoe and Brake drum: This should be ≤ 1.3055 mm
(iv) Brake and Clutch pedals in low position: The team member is educated not to press the brake pedal and
clutch pedal by putting the components tray in pedals and ensure that the pedals are in correct position
before filling the brake fluid.
(v) Improper clamping of gun seal packings: Workers are to be trained to place the gun seal packings properly
and appropriately clamp to the reservoir.
(vi) Damage in gun seal packings of brake fluid filling gun: Mock model of reservoir is developed to check the
pre-vacuum error.
(vii) Improper clamping of pressure seal clamp between gun to hose joint: Pressure seal clamp should be
clamped properly between gun to hose joint, and also pressure seal clamp should be checked once in a day
whether the leakage of pressure vacuum occurs.
(viii) Blockage of Vacuum filter: Vacuum filter has to be checked daily and if there is accumulation of dust,
clean it. Vacuum filter should be cleaned once in a week by using distilled water and dried before placing it
back.
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