Electromech Engineers has been commended for its technological excellence by international technical consultants. Our belief in continuous improvement and innovation has been well received by our clients and has been endorsed in the form of multiple repeat orders from big multinationals.

Given below are links for special technological features of various typical sub-assemblies of our products as well as some processes that go into making the product world-class.

• Main Girders and/or Portals
• End Carriage and Crab Frame
• Rope Drums
• Gear Boxes
• Wheel Assemblies
• Hook & Hook Blocks
• Motors
• Brakes
• Limit Switches
• Maintenance Platforms
• Power Supply to Trolley
• Control Panels and other electrics
• Resistance Boxes
• Assembly & Shop Testing
• Dismantling, Finishing and Dispatch
• Documentation

Main Girders are of all welded box construction. Plates used are of tested quality confirming to IS226 or IS2062. Section is selected based on the relevant clauses of IS807 /   IS800 / AISE6. The proportioning of the members ensures ample rigidity, rapid dampening of vibrations, minimum slenderness ration values. Besides tensile stresses, shear stresses and deflection for which the girders are normally checked, our design ensures that the compressive stresses, bearing stresses, torsional stresses, combined stresses and bending stresses on Cross Travel Rail too are within permissible limits. The design process is fully computerized to ensure the most optimum design.

Manufacture of the same under rigid supervision using well proven welding procedures and techniques by qualified welders ensures a near perfect box with pre-determined camber (as specified by FEM / IPSS). While codes specify only radiography of butt welds under tension, we as a routine, conduct 100% radiography of all butt welds and 100% dye penetrant check on all fillets.

The Main Girders being main structural members requiring no maintenance during the entire life span of the crane, special care is taken during the finishing and painting operations. All edges are ground. Mill scales, weld spatter and other foreign matter is sand blasted or brush cleaned. All oil and other impurities degreased and removed.Finally two coats of Red Oxide Zinc Chromate primer of DFT not less than 60 microns each are applied, both internally prior to closing the box and externally after completion of fabrication.

 

End Carriages and Crab Frame are manufactured using rolled sections  or plates and have a welded rigid design. All quality control and finishing procedures adopted for main girders are applied to above two structural members also. Generally designed and appropriately positioned jacking pads are provided for easy removal of individual wheels with minimum effort. The crab frame is fully plated with chequered plates with openings only for wire ropes emanating from the rope drum to pass. The frame is generously proportioned to ensure safe, easy, and ample access to all machinery above and below the crab frame to inspect and maintain the same during service. Two tired hand railings and toe guards on crab and end carriage ensure absolute safety during inspection and maintenance. End Carriages and Crab Structures are provided with derailing stiffeners at all four corners which prevent fall of structure by no more than 50 mm in the unlikely event of wheel axle failure.

 

Rope drums are designed and checked for compressive and bending stresses. Adequate ribbing and stiffening is done at the ends where support shafts emanate. All drums are double flanged and double grooved. The flanges are so proportioned that 2 rope diameter distance is the minimum outstand radially beyond the rope. Rope Drums are manufactured either from IS226/IS2062 plates or from Seamless pipes. Immaterial of length, circumferential weld seams are totally avoided. Welding of drums when fabricated are done using Low Hydrogen Electrodes under controlled conditions of temperature to minimize metallurgical damage in the HAZ. Long seams are 100% radiographed. Welded drums are stress relieved as per procedures laid down by ASME section IX in an approved furnace prior to machining.

All drums are double grooved, using form tools ensuring smooth transition resulting in minimum wear on ropes. Three bearing support of the drum is totally avoided. This is done by either supporting the drum on two independent pedestals on amply proportioned spherical roller bearings and coupling the drum shaft with the gearbox out put shaft using a full geared coupling or by supporting and coupling the drum to the gearbox by an integral geared coupling using internal and external crowned teeth and self aligning bearings at the gear box and free end.

 

All Gear Boxes are of totally enclosed Helical type.Gear Boxes are designed and manufactured, conforming to IS3177 and IS4460 or AGMA8 or better quality. Only metric modules of preferred numbers are used throughout. Corrected involute tooth profiles are used throughout to ensure adequate rating even when very low teeth numbers are used. The rating is based on the minimum of strength and wear HPs for a given pair, strictly as per IS3177 and IS4460.

Amply proportioned face width ensures sufficient overlap based on the axial pitch for a given module. Tooth composite error is maintained within permissible limits as specified in IS3681. Back lashes and peripheral speeds are maintained at levels as specified by IS4460.

The housings are fabricated, stress relieved and bored horizontally in one set up immaterial of gearbox size on a Horizontal Borer with DRO facility to ensure accuracy of centers as per AGMA Quality 8.

Gears and pinions are from C55 (EN-9), 40Ni2Cr1Mo28 (EN-24), 13Ni3Cr80 (EN-36), 20MnCr5 forged and heat treated appropriately. Teeth cutting using generation process and finish turning/grinding of support bearing diameters on pinion shafts/boring of bores on gears are done after heat treatment to avoid distortion in relation to bearing diameters and bores and PCD of teeth.

Bearings are generously proportioned to ensure life far in excess of life specified in IS3177. Dip sticks, Inspection covers, oil level indicators and breathers are standard accessories.

 

All wheel assemblies used in Trolley and End Carriages are of Live Axle Execution ("L" Type) (In Single Girder Cranes, all the wheel Assemblies are of the Dead Axle type) . The tread diameters are chosen from preferred numbers and the design strictly conforms to IS3177. The wheel forgings are from C55 (EN9) material suitably heat treated to 300/350 BHN. Axles are from C55 and the housing and bearing covers from MS profiles. The tread width is generous, allowing for substantial track alignment deviations. Bearings are Spherical Roller/Deep Groove Ball bearings amply proportioned.

 

Hook blocks consist of sheaves, sheave guard, trunion and hook. The design conforms to IS3177. Sheaves are of CS IS1030/MS profiles, running on anti friction bearings. Sheave guards are of MS construction, with openings only for wire rope to pass, ensuring absolute safety. Trunions are forged and amply proportioned, designed to resist bending stresses. Hooks are from EN3A, always provided with a spring loaded hook latch.

 

Ratings of motors for all motions are established strictly as per IS3177 recommendations. To establish the frame size, the calculated ratings are further uprated for the ambient conditions using factors as specified by IPSS. While calculating Hoisting Motor power requirement, weight of the full length of wire rope and snatch block is treated as load to be lifted. CT and LT power ratings and motor selections are further checked for skidding and the wheel size further enhanced should the need arise. Frame size selected are always optimal, ensuring best performance with minimum connected load. All motors are crane duty HI-Torque, Slip Ring/Squirrel Cage as per customer and operational needs of reputed makes such as Bharat Bijlee, GEC, KEC.

 

As a standard practice we provide adequately proportioned Electrohydraulic Thruster Brakes on all motions. The brakes are rated at minimum 150% of the full load torque of the selected motors. The brakes are always mounted on the input shaft of the gearbox on an independent brake drum coupling enabling easy access and maintenance. On request additional brakes on any motion could be provided. We could also provide on request, ACEM or DCEM brakes if required. Brakes of reputed makes such as Electromag, Speedo Control, EPC, BCH are used.

 

The hoisting motion is provided with a rotary limit switch. Additional gravity operated limit switch could be provided on request. The CT and LT motions are provided with lever type limit switches. If more than one crane is operating on the same bay, additional proximity switches could be provided on request. Limit Switches of reputed makes such as Electromag, Stromkraft, Speedo Control, EPC are used.

 

Full length chequered plate platform with hand railing and toe guards are provided on the drive side girder. Two short platforms of similar construction are provided on the idle side girder for the maintenance of idle side wheels. Full length platforms on idle side too could be provided on request.

 

Power supply to the trolley is normally through flexible festoon cables, mounted on robustly designed trolleys, running on either "T" track or "I" beam. The support structure is bolted to the idle side girder firmly.

 

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Control Panels and other electrics

Control panels are from 2mm thick CRCA sheets. The doors are hinged and gasketted. The internals consist of contactors of AC4 duty, relays, timers, fuses etc. all of reputed makes such as Siemens, L&T, BCH, English Electric only. The panels are completely pre-wired in cable channels and terminated on Elmex Terminals duly ferruled. At least 10% spare terminals are provided for maintenance. Bottom entry cable glands are used for wiring.

 

Resistance boxes of SS 10 minute rated grids are used as a standard practice where applicable. They are sourced from reputed manufacturers such as Electromag, Stromkraft, Speedocontrol or EPC.

 

All cranes are fully assembled, wired using its own panels and fully tested as per norms laid down in IS 3177. The shop tests routinely carried out are - Dimensional and No Load Speed Checks as per IPSS and IS standards. Full Load, Over Load and Speed Checks at Full Load are normally carried out at site after erection & commissioning.

 

Cranes once approved after testing by client/consultant and approved for dispatch are dismantled. All mating components are match marked. All welds rechecked and dressed. Final painting consisting of 2 coats of Synthetic Enamel of shade as per client's requirement applied. Control Panels, Resistance Boxes, Cables, Wire Rope, Snatch Block and small items are crated/boxed.

 

All cranes as a routine are supported with following documentation.

1. Shop Test Certificate of Crane
2. Manufacturer's Test Certificates for Hook, Motors, Wire Rope, Brakes
3. Lab Test reports or Manufacturer's Test Certificates for load bearing structurals
4. Radiographic films of all butt welds
5. General arrangement drawing
6. Electrical Wiring diagram
7. Operating and maintenance manual
8. Our Guarantee card