Bracket adjustment work in OHE

Bracket/Cantilever adjustment is crucial for the smooth operation of the electric engine’s Pantograph.

The parameters for bracket adjustment are vary project wise or client demand. We are explaining about bracket adjustment work in OHE on the basis of practical method.

There are two types of bracket/cantilever adjustment

1. Bracket adjustment work without super elevation
2. Bracket adjustment work in super elevation

Note- This Article is under progress, full details will be public on or before 10th November 2024

1. Bracket adjustment work without super elevation

1. Single bracket adjustment
2. Uninsulated overlap (UIOL) adjustment
3. Insulated overlap (IOL) adjustment
4. Adjustment on Box type bracket
5. Adjustment on cross-over

a. Single bracket adjustment-

Normally, the encumbrance is 1.4 meters and contact & catenary height depend upon project/client demand.

Let us consider, we want 5.6 meters contact height. Then height of catenary wire will be 7.00 meters with 1.4 meters encumbrance. Where contact height is required 5.8 meters, catenary height will kept at 7.2 meters.

Stigger

1. Contact Stigger should be less than or equal to +200 or -200 mm for straight line track.
2. Contact Stigger should be less than or equal to +300 mm for inside curve of the railway track.
3. Contact Stigger should be less than or equal to -300 mm for outside curve of the railway track.

Note:- a) Catenary stigger is kept zero in IR(EPC) project, While in DFCCIL project it remains dead-plumb with contact.

b)Keep the stigger as per given value in SED.

b. Uninsulated overlap(UIOL) adjustment

As discussed in the article no 5 that distance between starting point of the next shot & termination of previous shot is called Overlap-zone.

On the basis of insulation, overlap is two types.

1. Uninsulated overlap ii) Insulated overlap

On the basis of span, Overlap-zone are 2 types

1.  3- span overlap zone  ii) 4 span overlap zone

1. Uninsulated overlap(UIOL) adjustment in 3-span condition

In case of uninsulated overall, the horizontal gap between IR and OR is kept 200. Rest of the procedure is to be followed as shown in the picture

1. a) The starting point of the next shot is shown at point “a”.
2. b) At point “b” the IR wire of the previous shot and the OOR wire of the next shot are shown.
3. c) At point “c” the OR wire of the previous shot and the IR wire of the next shot are shown.
4. d) The termination of previous shot is shown at point “D”.

The height and strigger of IR and OR wire at these four points is kept as per the given chart.

Sr. No Point A, B, C, D

Height of IR

Strigger of IR

Height of OR

Strigger of OR

Horizontal gap between IR & OR

2. Uninsulated overall adjustment in 4 span condition:-

In case of uninsulated overall, the horizontal gap between IR and OR is kept 200. Rest of the procedure is to be followed as shown in the picture

a) The starting point of the next shot is shown at point “a”.

b) At point “b” the IR wire of the previous shot and the OOR wire of the next shot are shown.

b2) At point “b2” the IR2 wire of the previous shot and the IR1 wire of the next shot are shown.

c) At point “c” the OR wire of the previous shot and the IR wire of the next shot are shown.

d) The termination of previous shot is shown at point “D”.

The height and strigger of IR and OR wire at these four points is kept as per the given chart.

Sr. No Point A, B, C, D

Height of IR

Strigger of IR

Height of OR

Strigger of OR

Horizontal gap between IR & OR

c) Insulated overlap(IOL) adjustment

In case of insulated overall, the horizontal gap between IR & OR is Kept 500mm. Rest of procedure is to be followed as shown in the figure-1&2  chart-1

ii) insulated overall adjustment in 3 span condition:

ii) insulated overall adjustment in 4 span condition:-

d) Adjustment on Box type bracket-

In case of box type of cantilever adjustment, the encumbrance and stigger  should be .90 meters and  0 respectively.

Contact height and Top & bottom height is depend upon project/client demand.

e) Adjustment on cross-over-

In case of cross over, the following points must be apply

1. The encumbrance of main line & cross over wire must be 90 & 140 respectively.
2. The height of contact wire in cross over line should be minimum 5 cm above from the main line contact wire. Example: if main line contact wire is 5.60 meters then cross over contact wire should be 5.65 meters.
3. The gap between the cross over wire & main line wire should not be more than 10 cm at the obligatory location.
4. Track separation should not be more than 680 mm otherwise adjustment of obligatory cantilever is very difficult to set for smooth running of pantograph.

Let us consider, permissible height of the contact wire is 5.6 meters in any project & main line have +100 stigger with 350 mm track-separation (TS).

Then, the following parameters should be apply at site.

1. Catenary & contact height of the main line wire is 6.50 meters & 5.60 meters respectively (Encumbrance 0.90 m ).
2. Catenary & contact height of the cross-over line wire is 7.05 meters & 5.65 meters respectively (Encumbrance 1.40 m ).
3. The stigger of main line & cross over is +100 & -250 respectively with 10 cm gap.

2. Bracket adjustment work with super elevation-

1. Single bracket adjustment
2. Uninsulated overlap (UIOL) adjustment
3. Insulated overlap (IOL) adjustment
4. Adjustment on Box type bracket
5. Adjustment on cross-over

Do you know about super elevation in railway track? it not, let us tell you.

If outer edge/rail of the railway track is rotated with respect to inner edge/rail, it is called as super elevation. For more details information about super elevation click on this link.

Now let us know how to do bracket adjustment in super elevation.

1. Single bracket adjustment

Let us consider, super elevation is 100 mm on site and we want +200 stigger & 5.6 meters contact height with 1.4 meters encumbrance.

Formula, distance of replacement on gage = (Contact height/Gage length)x SE

DR = (5.6/1.67)X100

= 335 mm

In case of inside curve:-  

In case of outside curve:-

1. Uninsulated overlap (UIOL) adjustment
2. Insulated overlap (IOL) adjustment
3. Adjustment on Box type bracket
4. Adjustment on cross-over