SALEM REGION

having fleet of 2231 numbers of buses in 32 branches.

DHARMAPURI REGION

“Tamil Nadu State Transport Corporation (Salem) Ltd.,”with the operational jurisdiction covering the

Four Districts viz., Salem, Namakkal, Dharmapuri and Krishnagiri

functioning as two Regions named

BYM.GAJENDRAN

GENERAL MANAGER TNSTC(SLM) LTD.,

Date : 28TH APRIL 2017

PRESENTATION ON COST CONTROL OF TYRES –

USAGE OF EPDM FLAPS

Objectives

❖ To Maximize Tyre performance

❖ To reduce cost

❖ To reduce Tyre Puncture

❖ EPDM is a type of synthetic rubber and it is extremely versatile material that can

be used in a variety of applications.

❖ Ethylene and propylene are derived from oil and natural gas. One of the best

character of EPDM Rubber is it’s heat and weather resistant property which is

manifold superior than Natural rubber.

❖ The most important difference is how well they stand up to extreme

heat. When temperatures rise above 100º F (38º C) for more than a day or two,

natural rubber gets soft. This can lead to weaker air pulses and may stretch out of

place.

EPDM FLAPEPDM: Ethylene Propylene Diene Monomer

(Poly methylene)

PROFILE OF EPDM FLAP

➢ The ethylene content is around 45% to

85%. The higher the ethylene content, the

higher the loading possibilities of the polymer,

better mixing, and extrusion.

➢ The dienes, typically comprising from 2.5%

to 12% by weight of the composition.

RAW MATERIALS OF EPDM

➢ The main properties of EPDM are its outstanding heat,

Ozone, and weather resistance.

➢ Good resistance to steam, Polar substance, Ketones,

diluted acids and alkalines.

➢ Service temperature is -500 C to 1500 C .

PROPERTIES OF EPDM

EPDM FLAP NATURAL RUBBER FLAP

FLAP CONDITION AFTER USAGE

S.No Property EPDM FlapNatural

Rubber Flap

1 Weight (in kg) 2.8 - 2.9 1.9 - 2.0

2 Raw material Synthetic Rubber Natural Rubber

3 Hydrocarbon content 25 %, Min 45 %, Min

4 Ash content 5 % Max 5 % Max

5 Before heat ageing

a) Hardness, Shore A 50-60 50-60

b) Tensile strength kg/cm2, Min 100 90

c) Elongation at break, percent Min 450 400

6 After heat ageing

a) Change in Hardness, Shore A 0 to +5 Units 0 to +5 Units

b) Change in Tensile strength kg/cm2, Min-5 % of the

initial value

-20 % of the

initial value

c) Change in Elongation at break, percent Min-30 % of the

initial value

-35 % of the

initial value

MECHANICAL PROPERTIES OF EPDM/NATURAL RUBBER FLAP

https://en.wikipedia.org/wiki/Shore_Ahttps://en.wikipedia.org/wiki/Shore_A

➢ Withstanding high temperature and non volatile

➢ Lesser down time leading to reduced Man power

➢ To avoid flap and tube ‘Pop-out’ from rim slot under high inflation pressure

➢ Flaps are used multiple times while re-setting the tyres .

➢ Tube Life increased.

➢ Low electrical conductivity.

➢ Resistance to steam and water.

➢ Tyre Puncture reduced drastically

➢ Flap cracks not occured and puncture eliminated.

➢ Leading to increased Tyre Life

ADVANTAGE OF EPDM FLAP

S.No Particulars 2016-17 2015-16 Diff Percentage

1 No.of Tyre Puncture / Year (Approx.) 13897 16483 -2586 15.68

2 No.of Tyre Condemn / Year 10488 11697 -1209 10.33

3 Tyre Life (In Lakhs) 2.30 2.07 0.23 11.11

4 No.of Tyre failure due to Flap bite / Year 973 1496 -523 34.95

5Avg. Life of the Flap (Approx.) in Lakh

Kms ( EPDM Vs Natural Flap)2.50 0.50 2.00 400

PERFORMANCE COMPARISON

11955 11697 10488

196137207733

230181

0

50000

100000

150000

200000

250000

2014-15 2015-16 2016-17

NO OF TYRES CONDEMNED

TYRE LIFE IN KM

YEAR WISE TYRE PERFORMANCE

Radial – 75 %Nylon – 25 %

Radial – 75 %Nylon – 25 %

2.19

2.272.24

2.212.24

2.212.25

2.32

2.39

2.432.45 2.46

2.05

2.10

2.15

2.20

2.25

2.30

2.35

2.40

2.45

2.50

TYR

E LI

FE IN

LA

KH

S

MONTH WISE TYRE LIFE : 2016-17

17385 16483

13897

-2586

21421496 973

-523

-5000

0

5000

10000

15000

20000

2014-15 2015-16 2016-17

TOTAL TYRE PUNCTURE

FLAP CUT PUNCTURE

EPDM

DIFF

YEAR WISE TYRE PUNCTURE

DESCRIPTION

2014-15EPDM

FLAP NIL

2015-16EPDMFLAP 53%

2016-17EPDMFLAP 67%

2014-15 Vs

2015-16%

2014-15 Vs

2016-17%

NO. OF PUNCTURES 17385 16483 13897 -902 5% -3488 20%

FLAP CUT PUNCTURES

2142 1496 973 -646 30% -1169 55%

Note : 1. Flap cut punctures Nil in EPDM Flaps.2. During October 2016 onwards we are procuring 100% EPDM Flaps only.3. October 2016 onwards EPDM Flaps are procured in 1:1 ratio, earlier natural rubber

flaps used as 1:3 ratio.

PERFORMANCEEPDM VS NATURAL RUBBER FLAP

0.47

0.43

0.440.47

0.47

0.55

0.33

0.51

0.48

0.48

0.46

0.41

0.3

0.35

0.4

0.45

0.5

0.55

0.6

CPKM

MONTH WISE CPKM

7.197.17

7.157.19

7.177.19 7.20

7.257.29

7.407.44

7.46

6.95

7

7.05

7.1

7.15

7.2

7.25

7.3

7.35

7.4

7.45

7.5

TYRE FLOAT

MONTH WISE TYRE FLOAT

Rear wheel Fitment0 – 15 days

Front wheel FitmentNext 15 days

Front wheel RotationNext 15 days

Front wheel Disc Out After 45 days from day 1

Below 8 MM NSDshifted to Rear position

Sent to RT when NSD is 2 MM

25 % usage in Frontand 75 % usage in Rear

NEW TYRE UTILISATION STEPS FOR BETTER PERFORMANCE

ALTERNATE DAYSAIR CHECKUP

NYLON – 90 PSIRADIAL – 120 PSI

TYRE ROTATION DONE ONCE IN 15 DAYS

FOR ALL TYRES

SL.NO DESCRIPTION 2015-16 2016-17 VARIANCE

1 Tyre Life (Kms) 207733 230181 22448

2 Tyre Float 7.18 7.44 0.26

3No of tyres condemned 11697 10488 -1209

4 No of New tyres 11115 10238 -877

5 No of Flaps 13503 11342 -2161

6 Tyre Puncture 16483 13897 -2586

7 CPKM in Paise 52 46 -6

COMPARISON

Tyre SavingsNew Tyre Savings 877 Tyres

Float increase from 7.18 to 7.46 0.28 tyre per bus

Total Buses 2231

Savings

= (0.28 x 2231)

624 Tyres

Total Tyres savings (New tyres & Float) 1501 tyres

Total Tyres savings in cost

=1501 x 11835.00

=1,77,64,335

• All New Tyres should be fitted only in Rear Wheel position for first 15-30 days, then only moved to front wheel position.

• After 15-30 days the Tyre moved to Front right wheel position for 15 days, again rotated to front left position for 15 days.

• After completion of 45 days tyre disc out to be carried.

• 30 days run in front position to be moved to rear wheels.

• After 8 mm NSD, tyres to be shifted to Rear wheel and used only in Rear position.

• Rear wheel tyres (Original or RT tyres without repair) rotation to be done as RRO to RLI, RRI to RLO and vice versa every 15 days.

• Front & Rear usage fixed as 25% & 75% to avoid violation a system of new tyre movements incorporated through register and monitored by computer.

• Over size repair (3x1, 4x1) and Shoulder repair carried out tyres to be fitted only in RRO position. Further, wear may occur fast at Repair spot; hence it has to be monitored daily.

• Full Button tyres should be fitted in selected A -Class routes (Bad conditioned roads).It should be changed to other vehicles in 15 days.

• During Repaired tyres setting, repair spot should be faced towards lock ring side.

• To Avoid Mechanical defects , all unit assemblies like front axle, rear axle, all valves, clutch, gear box etc., were changed during F.C. Compulsory.

• Uneven Wear Reports to be rectified within 3 days.

• Wheel Alignment to be carried out once in 15 days.

• 2 mm NSD tyres (Original & RT) should be removed and sent to RT plant for re-treading.

• During Repaired tyres setting, tube mouth valve to be fitted 180 degrees from repair spot.

• More nos. of tyre rotation helps to increase tyre life.

• Uniform air pressure adopted as 90 psi for Nylon tyres and 120 psi for Radial tyres.

Good Practice for Tyre Maintenance to enhance better performance

• During 2015-16 & 2016-17 Nylon and Radial Tyre percentage were 25% & 75%.

• 2015-16 Tyre life is 2.08 lakhs Km.

• 2016-17 Tyre life is 2.30 lakhs Km.

• The above increased Tyre life achieved by improving better Tyre maintenance activities.

• From April-2017 onwards procurement percentage of Nylon & Radial Tyres are 10% & 90% respectively.

• In future we can achieve the Tyre life 2.60 lakhs km.

• Further our KMPL has increased from 5.58 to 5.63.

CONCLUSION

THANK YOU