Loco link is an arrangement of locomotive for working a set of trains from one station to other station for Mail/Express/Passenger trains. Loco link gives the requirement of locomotive required to run the given number of trains. Loco link is prepared by HQ office in consultation with COM.

Factors to be considered while preparing a loco link:

1) Availability of the Loco.
2) Trip Inspection:

Mail/Express or Passenger locomotives are required to be given trip inspection as under as per AC traction manual:-
After running of 3000 kms or at completion of a trip whichever is later.

Therefore, loco link has to be prepared in such a way that the trip inspection is done as per the yardstick and no loco runs overdue trip inspection in the link. Loco link should have the provision of the trip inspection at suitable interval.

3) Lie over period at destination station:

When a loco completes its journey after working a train, this loco is sent to yard, trip shed etc. This loco is again attached to the train as per the link. The period for which it remains idle at destination station (i.e. the time period when loco isdetached and again attached to train) is known as lie over period of the locomotive.
given to locomotive. Therefore, lie over period of locomotive is a loco link will depend on the following:-

A) Lay out of yard and location of trip shed :

If the locomotive is to be given trip inspection during the lie over period, the time (T) to be available during the lie over period should be as under:-

T = Time taken for trip inspection (Tt) + Time required for movement of loco from station to trip shed and back (Tm)

Generally, the time required for trip inspection is 2 hours to 2 hour 30 minutes. However, time is also taken to attend the drivers booking regarding loco defects.
On an average, it is seen that one hour time will be required to attend to various types of defects booked by drivers. Therefore, for trip inspection, time to be given is about 3’30” to hours considering the practical working in trip shed. Sometime, when loco arrives in trip shed, staff may be busy in dealing with the problem of other loco. In that case, loco has to wait. Therefore, allotting a time of 4 hours for trip shed in case
of trip inspection to be done is quite reasonable and practical.
Similarly, some time will be taken for movement of electric locomotive from station to trip shed. Again this time will vary from one destination to other.
Generally, trip sheds are located in the yard in such a way that loco can be moved  from station to trip shed within 30” time. However, due to variation in yard lay out and other operating condition trip sheds are to be located far away from station where engine is detached. In such situation, the time taken to move the loco from station to trip shed may be as high as two hours.

B) Whether destination in a terminus :

Moreover, if the destination of the train is CSTM or HWH or Madras etc. where the railway track terminates, the locomotive at such station cannot be immediately detached and sent to trip shed. Therefore, loco has to remain on station platform till the rake is backed to washing siding in the yard after about 45” from the arrival of the train. This aspect should also be taken into account while planning the loco link.
Practical example
Central Railway locomotives are reaching HWH after working the train like 12151 Samrasta Exp. As HWH is a terminus station and also the trip shed is located away from station at Santaragachi S.E. Railway requires a lie over period of 10 to 12 hours for trip inspection for the reason explained in above paras.

4) Consultation with other Railways/Divisions :

While planning the loco link, other Railway or division (where the loco will be detached and attention will be given) should be consulted for requirement of time for lie over period. Similarly, trip inspection schedule should also be planned and place should be nominated in the link.

5) Provision of Schedule Inspection (IA, IB or IC of loco) :

Loco link should include the withdrawal of loco for monthly schedule after it has worked for 35 to 40 days in the link. Withdrawal of the loco at Homing Shed station should be planned in such a way that it suits the homing shed by way of working hours for carrying out the schedule.
In electric loco sheds, normally locos are placed for schedule inspection at about 2 to
3 hours in (0-8) shift of working. This helps the homing shed in carrying out complete testing of locomotives by 8 hours. The staff in (0-8) shift will give complete detail of unscheduled work to be carried out along with schedule work.
This will enable the staff in day shift to carry out the work properly. Therefore, withdrawal of loco to be planned by such trains which reaches homing station at about 0 to 1 hour so that loco reaches the homing shed just in time. Therefore, withdrawal of loco to be planned while considering following points:

i. When to withdraw the loco – By suitable train so that it reached homing shed station at about 0 to 2 hours.
ii. From which train to withdraw the loco - This should also be decided judiciously after studying the working time table. there are some trains where time allowance and running time is sufficient, such trains can make up the loss of time which takes place while changing the engine for withdrawing the same for such inspection. Generally, for changing the engine 10” extra is taken for loco movement and vacuum creation. From this link in fig. (shown Next page) , we find that for running trains between Igatpuri-Nasik, Igatpuri-

Calculation of the requirement of engines:

The loco link gives the bare minimum requirement of engines. Therefore, the actual engine requirement will be as under:-
The requirement of loco = Bare minimum requirement + repair allowance.

The repair allowance for Mail/Express locomotives is 9.2 statistical. Therefore, requirements of locomotive will be :-
Bare minimum requirement as per loco link 0.92


In this subject, we have learned to draw loco link and also factors to be considered for drawing a loco link. More practical should be done to draw loco links from the Railway time table for better understanding.

Some example

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