The cranes shall be designed, manufactured, erected and tested in accordance with the following specifications :
BRIDGE GIRDER :
The bridge girder shall be fabricated out of mild steel plates welded together to form a box.
In addition to the required full length, short length diaphragms shall be inserted wherever required to transmit the trolley load to the web plates and to limit the maximum stress in the trolley rails within the safe permissible limits. All diaphragms shall bear against top flange.
END CARRIAGES :
End carriages shall be fabricated out of steel plates welded together to form a box. Suitable diaphragms shall be provided wherever necessary.
TROLLEY FRAME :
The trolley frame shall be fabricated out of steel plates and made rigid by providing suitable diaphragms. The frame shall be totally covered and openings shall be provided wherever required.
WIRE ROPE :
The wire rope provided shall be 6*36 or power form construction, Best plough steel, fiber/steel core having a tensile strength of 200 kg/mm2 and shall be of parallel right hand ordinary lay as per IS:2266.
The wheels of the trolley and the end carriages shall be forged out of EN9/C55 Mn75 material, double flanged, straight tread type fitted with anti friction bearings mounted on ‘L’ type bearing housing for the ease of maintenance.
ROPE DRUM :
The rope drum shall be made from mild steel seamless pipe designed to withstand the compressive stress due to beam action of the drum and shall conform to IS: 3177.
GEAR BOXES :
All gear boxes provided shall be of totally enclosed splash lubricated type. The gear box casings shall be fabricated out of steel plates and duly stress relieved. All gears and pinions provided shall be of helical type only.
Gears shall be from EN-9 forged/rolled material and pinion from EN-19 .The gears shall be designed in accordance with IS: 4460.
AC operated electro hydraulic thruster brake shall be provided on all motions of the cranes.
An additional EHT brake shall be provided on main hoisting motion of the crane.
Stainless steel Punched/formed grid well ventilated resistance box shall be provided. The resistance box shall be heavy duty, robust, corrosion resistant and rated for 5/10 minutes.
All motors shall be of Slipping/sq cage of reputed make like Marathon/KEC/Crompton, etc.
TROLLEY CONDUCTORS :
Power supply to the trolley shall be through PVC flexible trailing cable fitted on cable trolley moving on a separate steel track.
M.S. Chequered plate/anti skid plate platform shall be provided for full length on both side of the bridge girder./or two short on Idle side as specified in technical details.
Special type of flexible geared joints between the hoist and rope drum shall be provided. Universal couplings with floating shaft arrangement/Coupling shall be provided for the cross traverse and long travel motions.
LIMIT SWITCHES :
Hoist motion shall be provided with rotary type limit switch to prevent the hook from over hoisting and lowering in addition to the load operated limit switch.
Shunt lever type limit switch shall be provided on cross traverse and long travel motions to prevent the over traveling and traversing of the crane and trolley respectively.