8-Wheeler OHE Car — Specifications & Pantograph Maintenance Schedule

Salient Features — Full Specification Table

Lifting & Swivelling Platform — Full Technical Specification

Pantograph Maintenance Schedule — The Full Periodicity Ladder

Fortnightly Inspection Schedule (After Tower Wagon Enters Isolated OHE Section)

• Pan: clean and check for copper deposition, grooves, or abnormality — renew grease if necessary.
• Insulators: check for cracks and flash marks, clean.
• Main Springs: check for breakage.
• Raising & Lowering: pantograph should RISE GRADUALLY and slow down BEFORE touching the contact wire, without rebounding. While lowering, it should be FAST initially, then slow down as it reaches the collapsed position.
• Verify no foreign material on the pantograph.

IA Schedule (45 Days)

• Wearing Strips: remove excess grease/copper particles; check for grooves or breakage — PERMISSIBLE GROOVE DEPTH IS 1mm (replace if exceeded); check fixing screws for projection beyond strip surface, tighten loose ones, verify none missing; measure strip thickness — IF BELOW 3.5mm, REPLACE; check sharp edges/projecting particles with a file.
• Copper Shunts: check for damage/loose connection. When replacing a shunt: in the bimetallic plate, ALUMINIUM must touch the aluminium alloy part, COPPER side must touch the shunt — the aluminium alloy contact surface is rubbed clean with a metallic brush, then covered with conducting grease or natural vaseline mixed with zinc powder.
• Main Springs: visual check for cracks.
• Plungers: check the bow plunger for free sliding while pressing — if jammed, loosen the spring-box fixing sleeves and turn them about their vertical axis until jamming clears. For a 7 KG WEIGHT ON THE COLLECTOR, the collar must come down by AT LEAST 10mm.
• Insulators: clean foot insulator and operating rod insulator with spirit, wipe dry. Check insulator and arc horns for flashes — verify ARC HORN SETTING IS AT 200mm.
• Roof Bars: check for breakage, loose connections — SPECIAL CARE with aluminium bars.
• Lubrication: check graphite grease on the pan — if burnt/blackened/hardened, remove and apply new grease (QUANTITY REQUIRED: 750 GRAMS per pan on a modified pan-to-pan assembly). Otherwise, add a small quantity and wipe to form a triangular grease cross-section using a straight edge touching the strip and grease-plate edge.
• Raising and Lowering Times: after greasing, the time to reach 1.5 METRES from when the pantograph is first fed compressed air must be BETWEEN 6 AND 10 SECONDS. The lowering time from de-energising the operating valve until the pantograph rests on its stops must be LESS THAN 10 SECONDS. Both times are adjustable via the throttle valve.

IB Schedule (90 Days) & IC Schedule (135 Days)

IB Schedule REPEATS all IA-Schedule work, PLUS: oil the spring boxes of the pan and check spring tension; check and tighten all nuts and bolts.

IC Schedule REPEATS all IB-Schedule work, PLUS: mechanical parts (verify operation, visually check the frame for distortion/damage); throttle valve (check working, clean, lubricate with vaseline); servomotor (if giving abnormal sound during operation, drain the cylinder via the drain-plug cap, check for air leakage); lubrication (all articulation pin bearings and plungers); pan (check for uniform strip wear and horizontality); CONTACT PRESSURE — after greasing the pan, the thrust exerted upwards on the contact wire is checked by hanging a 7 KG WEIGHT on the head and varying height up to 2 METRES; thrust must be UNIFORM, adjusted via the main-spring adjusting screw if out of limit.

AOH Schedule (18 Months)

REPEATS all IC-Schedule work, PLUS:

• Servomotor: overhaul, lubricate cylinder walls with ALVANIA 3 GREASE; check piston packing for wear/damage; measure cylinder diameter — MAXIMUM ALLOWED DIAMETER IS 205mm.
• Lubrication: clean and lubricate pin bearings; lubricate ball bearings and thrust-rod articulations with Alvania 3 grease — ball bearings I and II have NO greasing nipples, so the cover must be removed to renew grease.
• Isolating Cocks: operate all by hand, return to previous position.
• Frame: check for bent or distorted pan/frame.
• End Strips: check for wear — MINIMUM THICKNESS REQUIRED IS 2.5mm; if grooves DEEPER THAN 2mm, replace the strips.
• Horns: check for cracks.

Overhaul During IOH/POH (Pantograph Removed from Vehicle)

• Bearings: after dismantling, check ALL ball bearings for wear of cage/ball, replace if necessary.
• Mechanical Parts: upper/lower articulation tubes dismantled and repaired if bent; middle articulation shaft triangular bracket, equaliser arm, etc. thoroughly checked for damage.
• Throttle Valve: dismantled and overhauled.
• Painting: old paint scraped, surface cleaned, BATTLE SHIP GREY paint applied.

Three Critical Overhaul Checks

• (a) Horizontality of Pan: if strip thickness differs by MORE THAN 1mm at both ends, check pan-arm horizontality with a spirit level — the pan MUST remain horizontal when raised to the full 1.5m height. If wear is concentrated on a particular length portion (from bent/distorted pins), the strip may be removed, straightened, and checked by jig. Also check whether pan cross-members are bent, by placing a straight edge across the wearing strips and moving it the pan's full length, observing edge-to-strip contact throughout.
• (b) Transverse Flexibility: raise pantograph to 1.5m, pull the pan transversely at the middle cross member with a 50 KG FORCE (checked by spring balance or a pulley-and-weight system). The displacement of the pan at the middle cross member SHOULD BE 36 ± 5mm.
• (c) Jigs and Fixtures: connecting tubes checked by jigs — a 25mm DIAMETER ROD passing freely through guide holes and bearing housing confirms no internal bending; upper articulation tubes passing freely through grooves confirms cross-member condition. Pantograph sitting correctly on FOUR BOLTS confirms base integrity; distortion of pan and vertical raising is checked by a frame-fixed rod; the stand supports the pantograph during spring repair.