SERVICE CIRCULAR
TATA MOTORS
Model : LPO 1618TC, LPO 1512 TC, LPO 1613CNG
SC/ 2009/
2009/ 32 Group : 00 Oct’09
BS-
BS-III
All Dealers / TASSs’
TASSs’
Subject: Introduction of New Generation front engine buses for JNNURM.
We are pleased to inform you about the launch of Front Engine buses for Jawaharlal Nehru
National Urban Renewal Mission (JNNURM) meeting BS-III norms. The models are:
• Diesel – LPO 1618TC & LPO 1512TC
• CNG - LPO 1613 CNG
All these vehicles have reduced chassis frame height to 840 mm to meet JNNURM norms of 900
mm bus floor height. This has been achieved by following modifications:
1. Outriggers on chassis frame to enable body fabrication without extra support
2. Hump on the chassis frame to have adequate stroke of rear axle
3. Suspension : Front – Weveller Rear – Air suspension
LPO 1618TC & 1512 TC Fully Built Bus LPO 1613CNG Chassis
We are enclosing the following details :
1. Salient Technical Specifications (Annexure -1)
2. Salient features (Annexure -2)
3. Warranty / Free Service details(Annexure -3)
CUSTOMER CARE (COMMERCIAL VEHICLE BUSINESS UNIT)
(As per policy of Tata Motors to continuously improve their products, the company reserves the right to make changes
of any nature on vehicles and aggregates without any obligation to incorporate them on previous vehicle)
Annexure - 1
Salient Technical Featutrs:
Following are the salient technical specs in new generation vehicles:
Technical Specifications
Bus Model
Aggregate
Diesel CNG
LPO 1512TC LPO 1618TC LPO 1613CNG
Engine
Cummins 6 BTAA Diesel New Recipe Engine 697 Naturally Aspirated CNG
Clutch 352 Dia Single plate dry friction 330 Dia Single plate dry friction
Gear Box G600. 6 forward,1 Reverse GBS 40. 5 forward,1 Reverse
Front axle I - beam reverse Elliot 1516 type
Rear axle RA 109 RR
Steering Rane Hydraullic Power steering
Full air S cam dual Full air S cam Dual
Brakes Full air S cam dual circuit
circuit circuit NGT brakes
Frame Conventional ladder type frame with hump at rear
Suspension Front - Weveller Semi elliptical leaf spring , Rear - 4 bellow air suspension
Wheel base 5545 mm 6200 mm 5545 mm
Overall
11122 mm 11850 mm 10645 mm
length
24V, Alternator - 60A, Battery -
Electricals 24V, Alternator - 75 A , Battery - 2X12V,150Ah
4X6V,150Ah
Annexure - 2
Salient Features:
Engine: New Recipe Cummins Diesel BS-III engine with improved parameters
Design Parameter Conventional New Recipe BS-III
Compression ratio 16:01 18:01
Injector Nozzle type DSLA480cc KS DLLA480cc K/HE
Peak power 98 KW @ 2500 RPM 100 KW @ 2500 RPM
Peak Torque 450 Nm @ 1500 RPM 470 Nm @ 1500 RPM
Advantages:
• Rotary FIP with improved emission characteristics
• Better fuel efficiency ( Kmpl )
• Improved injector nozzles against clogging tendency
Chassis Frame: With lowered height of 840 mm.
Hump on Chassis
840 mm
instead
ins tead of
earlier 900 mm
Outrigger type frame design to facilitate body building without extra support
New Generation Truck Brakes (NGT)
Design modifications in NGT over conventional brakes :
(i) Brake liners dimensions (mm) : Conventional NGT
Width Front 160 200
Rear 180 220
Thickness Front 16.5 20.5
Rear 16.5 20.5
(ii) Higher system operating
operating pressure of 9 bar against 8.1 bar for conventional
Pressure reduction Valve (PRV) added in the circuit for regulation to individual pneumatically
operated units as:
NGT Conventional
Reduced to 7.5
Air Suspension Constant 8.1
from 9 bar
bars for all as
Retarder 4.5 bar
there is no PRV
Door 6 bar
Suspension:
Front : Weveller semi elliptical leaf spring type which does not need shackles , hence contributes
in lowering of chassis frame height . The bush & pin type mounting is replaced by rubber blocks,
which insulates shocks. This design permits limited longitudinal motion of the spring ends due to
rubber blocks at the ends.
Front Rear
Advantages:
• Better isolation of road shocks
• Greasing is not required
• Replacement of rubber is easy as compared to bush /pin arrangement
Rear Air Suspension:
Suspension:
(a) General Description : 4 nos. of air springs are mounted on horn bracket assembly at rear. The
horn bracket assembly, as shown under the rear axle beam is fastened through U bolts to the axle.
(b) Layout of Pneumatic Suspension components
1
1
1. Control Arms
2. Antiroll bars
4 2 3. Cow Horn Bracket
3 assembly
4. Air Spring
5. Shock Absorbers
(c) Specifications :
• Static Installation Height (From Top Plate bottom to Piston base) - 240 mm (common for
LPO 1512 /1618 TC Diesel , LPO1613 CNG )
• Design height -140 mm, Assy weight -1.4 Kg, Height: 170mm (min.)/ 450mm (max.)
• Leveling valve: WABCO 4640024400, Loading capacity -23 KN@5 bar, 31KN@ 6.5 bar
(d) Adjustments:
Static installation height for air spring is to be checked at every 18000 kms, for correct value. This
is necessary because its variation from the designed specification causes poor ride quality for
passengers and may result in excess wear / failure of suspension. Static Height is adjusted by
varying the leverage of connector rod. This can be done by adjusting the nut provided on the
leverage rod. In order to increase the static height, length of leverage rod has to be increased by
adjusting the nut in anti clock wise direction. In order to decrease the static height of the air
suspension system, length of the static rod has to be decreased by adjusting the nut in clockwise
direction.
A- Leveling Valve Checking static height :240 mm Adjusting leverage rod B for setting
setting
B- Leverage Rod air spring static height
(e) Precautions:
Precautions
1. Don’t disturb the leveling valve lever position.
2. Don’t change the air spring static height as it affects the ride comfort
3. Don’t over torque leveling valve mounting bolts as this will lead to breakage of valve body.
4. Don’t use sharp edge tools to remove diaphragm from piston and clamp plate assy since it will
damage the diaphragm beads.
5. Don’t drive the vehicle without shock absorbers.
6. Don’t drive the vehicle without Air in the Air spring Assy.
(f) Trouble Shooting:
Shooting
S.N. Complaint Cause Solution
(a) Undampened
Shock absorber oil leak -
motion - Vehicle Replace shock absorber
damping loss
keeps oscillating
(b) Vibration Worn out bushes Replace bushes
1 Poor ride Levelling valve
Correct lever posiotion , service
malfunction , incorrcet
leveling valve
(c ) Bumpy ride lever position
Incorrect air spring static
Correct air spring static height
height
Loose bolts Retorque bolts
2 Noise
Worn out bushes Replace bushes
Correct levelling valve
Air spring static height Service levelling valve position
3 Vehicle tilted difference between LH/
Check for air leak in clamp plates ,
RH
piston , pneumatic fittings & arrest
Annexure - 3
Warranty / Free Service: The warranty norms & free service schedule are as per JNNURM tender
details for the respective model.
