Sunday, September 24, 2017

About loco bearings and centre pivot

If failure of Racers occurs in WAG9 locos, procedure to mount axle should be inspected in the shop.:

G9 Racer is induction heated before fitting over the axle journal. ( two racers on each side ).

Axle box     and          Racer        Bearing in above and below snap.

Due to failure of induction heaters, gas heated racers may get the profile damaged and this may result in failure. B 
The radial clearance measurement procedure ( different for SKF and FAG racers ) should be followed with the help of NO-GO gauges.

Centre Pivot:

Castings need to be rejected during machining if there are  large number of blow holes.

Blow holes in Centre Pivot of WAP4 ( Raj ) locos loo like this:

Force fit Racer of WAP5 locos should be  examined while fitment.

Friday, September 22, 2017

Traction Motor of Locomotive

How to do Backlash measurement of pinion-gear ? 

IN TM shop was   following problems can be analysed:-.

When three teeth match, filler gauge is used to make one side gap NIL, then clearance between other side gives the backlash.

Pinion Draw measurement to be inspected.
a)    Color matching ( more than 90% ensured) sould be done for proper interference between two surfaces.
b)   Pinion inserted.
c)    Pinion drawn out , induction heated and again inserted.
d)   Pinion draw= ©-(b)

Lateral and longitudinal bogie clearances can be measured as in above picture .

Shown in above: Modified stator clamps to hold bracing ring which protects overhang portion from vibrations .

Greasing nipple and bearing cover groove matching is necessary for proper greasing in HITACHI motors.  

The bearing cover groove , if not in matching location, results in blockage of path. This cover is supposed to be shrink fit but is press fitted in the shop.

Monday, September 18, 2017

Care while inspecting locomotives

Bulk head measurement in the cab should be observed in shop. If some trade cabs have over-sized bulk heads,  Inspection staff should not   pass any such cab.

Camber measurement with Dumphy Level (a kind of theodolite) should be inspected. Shown in above picture taking the camber measurement in underframe.

Anti collision post of WAP5 should be  measured for dimensions in the shop.


Below is the snap of TG Anti Collision Post.

It is to be observed that gap measurement between two posts is in the standard C&D format.

Non-standard nut of transformer mounting bolts should not be allowed( if found during shop inspection that nuts are under-sized) and we should not   generate movement slip  .

What should be checked in a new locomotive

What is to checked in new  locomotives  to be dispatched ?
HT Cable touching the wall is one such item and should be  addressed by a suitably putting a packing  

Another NC observed : absence of sealant in machine room  blower pipe which results   in air leakage.

Loco should have no   gaps between sheets of cab dashboard which will result in dust ingress.

All quality officers should be consulted for checksheet points to be recorded in register but  

in “format’ ; following points could be enlisted:-
1.              Brake hanger pin check nut in 3-ph loco.
2.              Gap in between compressor legs and compressor bracket in 3-ph loco.
3.              Dimensional alignment of vertical damper bracket from loco centre line in 3-ph loco.
4.              Gap measurement between brake hanger bracket and bogie frame.
5.              Buffer height and bogie body vertical & lateral/ clearance checking.
6.              Light passing test to the roof of the shell of locomotives.
7.              Gap in between central underframe and transformer mounting plate in 3-ph loco.
8.              Standardisation of permissible waviness in sidewall/ shell to extent of ±6mm.
9.              Rationalising the standard of pressing force for gear and wheel.

Type of Loco
Old standard
New standard
WAG – 7, WAP – 4 
Gear: 89 to 117 ton
Wheel: 95 to 132 ton
Gear: 95 to 110 ton
Wheel: 100 to 125 ton
WAG – 9, WAP – 7
Gear: 92 to 104 ton
Wheel: 80 to 102 ton
Gear: 95 to 100 ton
Wheel: 85 to 100 ton
WAP - 5
Gear: 88 to 108 ton
Wheel: 80 to 104 ton
Gear: 95 to 105 ton
Wheel: 85 to 100 ton
10.           New three check  points introduced to measure axial end play in MSU (motor suspension unit) of wheel sets as per RDSO’s & study.
11.            Extra channel has been introduced in side wall of WAP-5 locos to reduce waviness.
12.           Standardisation of vibration and noise level to the extent of 4.5 mm/sec and 110dB to all traction motors fitted in Bogie Shop of Motorised Bogie.

13.           Air velocity measurement in machine room for 3-ph locomotives.

14.           Welding of arch cross member of roof fitment has been modified to arrest rainwater leakage.

15.           New template introduced for checking verticality of cab door frame.
16.           New template introduced for checking compensating and equalising beam of conventional locos.
17.           Fixture and welding procedure has been modified to maintain parallelism of two vertical plates during fabrication of long beam to minimise side deflection in 3-ph locomotives.
18.           Raising the sand box for 3-ph locomotives. This will reduce the chances of damage of sand box during cattle run over and ballast hitting.
19.           Additional BP cock in brake pipe as recommended by RDSO.