Trolley / Cab of Locomotive Inspection of OHE
Inspection of OHE by push trolley enables supervisors and officers in charge of OHE maintenance to closely observe the OHE under their charge, and should be carried out during daytime.
| Role | Trolley Inspection Frequency |
|---|---|
| Depot/OHE in-charge (SE/JE) | Once a month, entire section |
| SSE/ADEE (TRD) | Once in 3/6 months, respective section |
| Sr.DEE/DEE (TRD) | At least once a year, entire section, by push trolley or motor trolley |
Apart from trolley inspection, officers and senior supervisors shall travel in the cabs of locomotives and EMU trains AT LEAST ONCE A MONTH to observe the general condition of OHE and gain first-hand knowledge of operating conditions.
Periodical Overhaul (POH) — Purpose and Interval
The object of POH is to recondition and restore the installation to the condition it was in when first commissioned — whereas preventive maintenance takes care of wear and tear during normal service and forestalls possible failures through regular inspection and quick attention. POH should be thorough and cover EVERY PART of the installation. POH of OHE is intended on a PROGRAMMED BASIS AT AN INTERVAL OF 4 YEARS. Its aim is a thorough inspection of the OHE, replacing worn-out or damaged parts with parts that have already been reconditioned in the maintenance depots and kept ready. Removed parts are sent to maintenance depots for dismantling, thorough inspection, and reconditioning. Everything covered under annual maintenance is additionally attended to during POH.
8.1 POH of Cantilever
During cantilever POH, eight specific dimensions are recorded against SED values, following the naming convention below (see the manual's Figure 25 for the single-bracket diagram these letters refer to):
| Symbol | Description |
|---|---|
| a | Distance between mast stay-arm fitting and the centre of the catenary suspension bracket |
| b | Distance between the axis of the vertical swivel and the axis of the catenary suspension bracket |
| c | Distance from the bottom cap of the bracket insulator to the axis of the register-arm hook |
| d | Horizontal distance between the centre of the register-arm hook and the axis of catenary suspension |
| e | Encumbrance — the distance between the axis of catenary and contact wire |
| f | The distance between contact plane and mast bracket fitting |
| r | Distance between contact plane and register-arm axis (assumed horizontal) |
| h | The vertical distance between top fitting and bottom fitting |
- AT LEAST ONE complete cantilever assembly PER 10 TRACK-KM should be removed and taken to the depot/workshop for dismantling and detailed examination of components after thorough cleaning — this test check reveals the extent to which other cantilever assemblies need examination.
- All GI fitting pipes are examined for deterioration of galvanization — minor chipping may be repainted with cold galvanizing paint.
- Aluminium bronze fittings, bolts and nuts are cleaned and carefully checked — threads must be in good condition; any fittings with cracks or deformation are ALWAYS discarded.
- As the bracket is articulated, its position (relative to the mast axis) varies with temperature and distance from the anti-creep — the register arm and steady arm should be in the same plane as the bracket.
- Adjustments of cantilever assemblies, their slope, and displacements are checked at every structure for compliance with the 'as-erected SED'.
8.2 POH of Regulating Equipment
In the POH schedule, a complete set of drum/pulley is removed from the mast and a new overhauled set replaces the old one — done very carefully to avoid line failures. All regulating equipment is replaced by previously-overhauled/new ones, and the removed equipment is sent to depot/workshop for overhaul. The regulating equipment is dismantled and every part checked and cleaned (using kerosene and cloth).
- Bearings MUST be replaced after each POH with a NEW bearing procured from the manufacturer or its authorized representative — bearings must be removed using a bearing puller jig with due care; hammering with local arrangement must NOT be done as it may damage housing/bearings.
- Rubber washers/rings are replaced where necessary; any grazing/rubbing on pulleys is repaired if possible, or the damaged equipment replaced. All lubricating holes are kept free for passage of grease.
- The stainless steel wire rope is checked thoroughly through a magnifying glass for loose wires/strands, broken wires/strands, rusting, pitting/corrosion, and bird caging — if any of these defects is observed, the wire rope is IMMEDIATELY replaced with a new lubricated wire rope. Particular attention is given to end fittings on the SS rope.
- The pulley, bent arms, and bearing housing are checked for any change in dimension — if deformed, repaired/replaced. Only approved-type lubricant is used for regulating equipment components.
8.2.1 Replacement of ATD at Site
After obtaining a power block with proper message confirmation, testing, and putting discharge rods on the OHE: (1) measure X, Z & Y values and analyse for adjustment during the schedule; (2) put come-along clamps on contact and catenary wire; (3) using a pulley arrangement, put a tirfor of 3 tons for the OHE and 1.5 tons for the balance weight; (4) take load so as to lift the balance weight and pull the catenary, releasing the ATD drum/pulley set; (5) remove the old set and fix the new overhauled set; (6) set the OHE and balance weight in its original position; (7) re-measure X, Z & Y values.
8.3-8.8 Other POH Items
- 8.3 Catenary and Contact Wire: dismantle all jumpers/clip connections and clean conductors — emery paper for copper/bronze, metallic brush for aluminium conductors. Wires showing overheating signs (loose tightening or deformed clips causing insufficient contact surface) need clip replacement. Contact wire groove is cleaned with a fine metallic brush or emery paper — use of a scraper or file is FORBIDDEN. Remove kinks if found.
- 8.4 Jumpers and PG Clamps: all jumpers/PG clamps are replaced by previously-overhauled/new ones; removed ones sent to depot/workshop for overhaul. Checked for damage/fraying, cleaned thoroughly, with proper bonding and tin soldering of jumper ends. Oxide is cleaned from PG clamp surfaces with emery paper (copper/bronze items); rusted bolts/nuts/washers replaced during POH; corrosion-inhibiting compound applied.
- 8.5 Insulated and Un-Insulated Overlaps: check position of contact wire relative to tracks complies with SEDs; ensure insulators of anchoring wires cross the plane of OHE correctly per plan.
- 8.6 Overline Structure: check height/gradient of the contact wire, adjust per drawings; check long-time and short-time clearances.
- 8.7 Overhead Cross-feeder, Return Conductor and 25kV Feeder: check wires for frayed strands, overheating, pinching, or corrosion (especially at suspension/PG clamps); ensure joints are properly coated with Vaseline during PG clamp tightening; check/adjust tension. Bypass feeders and earth-wire insulator attachments are dismantled, cleaned, overhauled, and repositioned.
- 8.8 Contact Wire & Catenary Wire Ending Clamp: visual inspection during every POH (once in 4 years); the FITTING ITSELF is replaced once in EIGHT YEARS (alternate POH), with necessary adjustment carried out at that time.
Re-tensioning of Unregulated OHE
Re-tensioning of unregulated OHE, in accordance with the tension-temperature chart, should be done normally at the end of 6 MONTHS from the date of erection, and again at the end of 12 MONTHS. Thereafter, tension should be checked ONCE IN 2 YEARS and re-tensioning done as required.