‘ELMECH’ E.O.T Cranes are manufactured keeping in mind the following basic objectives.
FLAMEPROOF EOT CRANES
TECHNICAL DESCRIPTION
INTODUCTION :
‘ELMECH’ E.O.T. Cranes are manufactured keeping in mind the following basic objectives.
1. High Quality.
2. Minimum Maintenance.
3. Aesthetic Appearance.
The above objectives are achieved incorporating certain advanced technical features described in the following pages.
ELMECH Cranes are designed keeping in mind Indian Standard Specifications applicable to the Cranes, viz.
I. IS:807-2006.
Code of Practice for Design, Manufacture, Erection & Testing (Structural Portion) of Cranes & Hoists.
II. IS:3177-1999 [with latest amendments].
Code of Practice for Design of Overhead Travelling Cranes & Gantry Cranes other than Steel Mill Cranes.
III. IS:4137-1985.
Code of Practice of Design of Steel Mill Duty Cranes.
ELMECH Double Girder Cranes are classified as Class I, II, III & IV OR Class M1 to M8. These Cranes are available in capacities ranging
from 1 Tonnes to 100 Tonnes.
STRUCTURAL ASSEMBLY.
This basically comprises of two bridge girders fixed on two End Carriages carried on forged steel wheels. In case of Gantry Cranes the two bridge girders are fixed on top of four Gantry legs which in turn are carried on two under carriages provided with forged steel wheels.
The bridge girders are fabricated from high quality steel plates forming a rectangular box section. Stiffening diaphragms are fitted at regular intervals for the design to conform to IS:807 and IS:800. The Girders are so built that they have the required cambre in the unloaded conditions as required under Indian Standard Specifications.
The internal surfaces are adequately sealed from the atmosphere by welding thus preventing internal corrosion.
The box type of girder construction has the following definite advantages over lattice and other type of constructions :-
More Torsional Rigidity: Box type of Girders have much more torsional rigidity than any other type of girder construction. Heavy torsional movement due to starting, stopping and plugging of long travel mechanism and also eccentrically placed masses like long travel machinery, calls for torsionally rigid girders.
VI. Streamlined and aesthetically pleasing appearance.
V. Ease of maintenance and cleaning.
VI. Limited chances of damage to structure during transportation :
A suitable track is provided on top of the Girders for the travel of the trolley (crab).
The End Carriages are fabricated from M.S. Plates and provided with necessary diaphragm members. These are connected to the girders using only machined bolts.
A tapered plate design is incorporated for joining the End Carriages to the Girders thereby ensuring smooth flow of stresses. This design is ideally suited for Cranes which are constantly subjected to dynamic loading.
The End Carriages are provided with forged steel wheels carried on specially designed bearing support blocks of ‘L’ type design (commonly known as ‘L’ type bearing Housings).
This method of providing wheels on ‘L’ type of blocks with antifriction bearings has the following advantages :-
1. It provides two load bearing surfaces at right angles to each other as against simple plummer blocks which provide a single bearing surface only.
2. Wheel load due to skewing of the Crane as well as the crab is transferred to the structure through machined grooves, the bearing housing and the machined pad welded to the structure, hence no undue stress is developed due to bending and shear on the holding bolts.
3. Wheels are press fitted on axles supported on spherical roller bearings which can withstand more axle thrust, bending and linear expansion due to temperature rise.
4. Complete wheel assembly can be changed within no time, since it is supported on only four bolts which otherwise can hold the Crane in breakdown condition for quite some time.
The End Carriages are provided at four corners with Rubber Buffers. At the end of the trolley track, M.S. curved End Stoppers are provided which act as trolley buffers.
The Trolley frame is fabricated from M. S. Plates / Rolled sections welded together to form robust construction to carry the hoisting and traversing machineries. The trolley frame is also carried on four forged steel wheels provided in ‘L’ type of bearing support blocks, the advantages of which have already been enumerated above.
One full length platform of chequerred / M. S. antiskid plates is provided on the drive end side of the bridge girders. Platform on other side can be provided at optional extra cost.
For easy assembly / erection at site all parts of Crane structure is match marked.
CABIN :-
In case of Cabin operated Cranes the Drivers Cabin is provided on one end of the bridge girder. The joint of the drivers cabin to the bridge girder is so designed that the cabin becomes integral with the girder. A step ladder is provided from the Cabin to the Crane Bridge Platform.
The Cabin is equipped with an Oscillating Fan, A Seat, an Electric Hooter and a Light for Illumination.
The Drivers Cabin is open/close type depending upon Indoor/Outdoor operations.
The Crab frame is fabricated from steel sections and carries the hoisting & cross travel machinery.
HOIST MOTION :-
This comprises of a motor of sufficient power, a totally enclosed helical gear box, a rope drum coupled to the gear box by a specially designed flexible coupling.
The motor is directly coupled to the gear box and on the coupling an Electro Magnetic / Electro Hydraulic Thruster Brake is provided which comes into operation as soon as the power is switched off.
The Gear Box is fabricated from M. S. incorporating all machine cut helical gear trains and is oil splash lubricated. The use of totally enclosed helical gear boxes though rather expensive more than justifies the extra price in view of the advantages of high transmission efficiency, less meshing noise and longer life.
The Gear Box is coupled to a M. S. Fabricated / Seamless pipe Rope Drum. The Rope Drum is finally machined to have right and left hand spiral grooves to take the hoisting rope. It is of such a size that there will not be more than one layer of rope on the drum when the rope is fully wound. Also the length of the drum will be such that each lead of rope will have minimum two full turns on the drum when the hook is at the lowest position and one spare groove for each rope lead when the hook is at the highest position.
A specially designed geared flexible couplings is provided to connect rope drum and the hoist gear box. The main advantages of this system are :-
1. It eliminates any alignment problem thereby avoiding strain due to basic misalignment in the output shaft hence preventing fatigue failure.
2. Vertical load is taken by a spherical roller bearing and the torque is transmitted separately through a geared coupling and shear pins. Hence there is no bolt to develop compound stresses due to shear and bending in each cycle of rotation of the drum. This avoids fatigue failure in bolts joining drum and gear box.
3. Dismantling and reassembling of hoist gear box and rope drum for maintenance becomes very easy there by considerably reducing the downtime of the crane.
A steel snatch block, complete with forged steel hook carried on ball thrust bearings is provided. It is provided with cast iron or fabricated M. S. Pulleys and is fitted with guards to prevent the rope from leaving the pulleys. Lifting Hook is tested as per IS:3815 / IS:15560 and IDLE test certificate is issued for each hook. Each lifting hook is provided with spring latch.
The Hoisting Wire Rope provided is of 6x36 or 6x37 construction of best plough steel having a breaking strength of 160/180 kg/mm2. The Wire Rope has factor of safety as stipulated in IS:3177-1999.
A spindle Limit Switch driven by Hoisting Drum Shaft is provided to give protection against the extreme positions of Hook Travel.
In case an Auxiliary Hoist is provided in addition to the Main Hoist, the principle and the Construction of the Auxiliary Hoist will be similar to the Main Hoist.
MICRO (CREEP) SPEED :-
In case of MICRO (CREEP) SPEED arrangement required, any one of the following system can be offered :-
A. Through Variable Voltage & Variable Frequency (VVVF). This is a latest technology arrangement due to which Stepless Pre-determined Slow Speed Variation is achievable from “0” to Full Speed, in all Motions.
B. Through Additional Unit comprising of Planetary Gear Box, Squirrel Cage Pony Motor & Reverse Thruster Brake Arrangement. As there is no Magnetic Clutch, this arrangement is fail-safe as well as long lasting.
C. Through Additional Unit, comprising of Gear Box, Magnetic Clutch & Squirrel Cage Pony Motor Arrangement. The shaft of the main Hoisting Motor will have double extension shaft. An Electro Magnetic Clutch will be fitted between the main motor and the output shaft of the Micro Speed Gear Box. The input shaft of the Micro Speed Gear Box is connected with Micro Speed Motor through flexible coupling. When the Micro Speed Motion is put on, the main brake opens while the Main Hoist Motor is not energized. The Magnetic Clutch energizes along with the Main Brake and drive is obtained through the Micro Speed Motor, the Slow Speed obtained due to the additional Micro Speed Gear Box.
TRAVERSE MOTION :-
The Traverse Motion involves power transmission from the motor to the trolley wheels through a totally enclosed vertically mounted spur gear box having an output shaft extending on both sides and driving the trolley wheels through semi-geared couplings on the principle of floating shaft. The Motor is directly coupled to the Gear Box and on the coupling an Electro Magnetic / Electro Hydraulic Thruster Brake is provided. The Brake applies automatically when the current supply is switched off.
A Two-Way lever type Limit Switch is provided for protection against the extreme traverse of the trolley (Crab).
TRAVEL MOTION :-
There are two ways in which this motion could be provided on Cranes :-
SINGLE DRIVER ARRANGEMENT:
In this case the power is transmitted from the motor through a centrally located horizontally mounted totally enclosed, helical Gear Box having an output shaft extended on both sides which drives the bridge wheels one on each End Carriage on the principle of floating shafts through semi-geared couplings.
The Motor is coupled to the Gear Box having all stage helical reductions and on the coupling is provided an Electro Magnetic / Electro Hydraulic Thruster Brake which applies automatically when the power is switched off.
TWIN DRIVE ARRANGEMENT:
In this case, two independent driving units are provided at each end of the Bridge Girder. Each unit comprises of a Motor driving, the bridge wheel through a totally enclosed helical Gear Box. The Motor is coupled to the Gear Box and on the Coupling an Electro Magnetic / Electro Hydraulic Thruster Brake is provided which applies automatically when the power is switched off. The Gear Box shaft extends on one side and drives the wheel on the principle of the floating shaft through semi-geared couplings.
THE SYSTEM of providing a semi-geared and semi-rigid coupling in the traverse and travel transmission shafting is known as the floating shaft system. This system has the following advantages :-
A. It prevents misalignment of the line shaft due to basic misalignment and improper maintenance.
B. It prevents misalignment arising out of differential deflection of crane girders and shafts.
C. It prevents development of any undue strain in the platform support which otherwise may give way due to excessive alternate stresses developed in the line shaft with rigid couplings.
D. For both Single Drive Arrangement OR Twin Drive Arrangement, LT End Carriages will carry 4 Nos. Double flanged Wheels supported on ball/spherical roller bearings running in “L” type housing.
E. Two Way lever type Limit Switch is provided for protection against extreme travel of Crane.
The entire transmission system on the output shafts of traverse and travel motions is designed with the use of geared couplings which has the following advantages :-
1. Simple in design and composed of few parts.
2. No Springs to crystallize or break.
3. No Rubber bushes to require frequent replacement.
4. It is self aligning with no binding action at any point of its revolution.
5. Crowned teeth are free to align themselves as in ball and socket joints.
6. Can be used on reversing service without any noise or vibration.
7. Exceptionally long life.
8. Simple to align, install and easy to maintain.
9. In capacity of transmitting torque it is the smallest in size and weight in comparison with any other flexible couplings.
ELECTRICALS :-
The Electrical Equipment comprises basically of Motors, their controls and wiring, etc.
CONTROLLING EQUIPMENT :-
The Controls for the Crane are of three types :-
(A) Cabin Operated Cranes. In case of cabin operated Cranes, there are two types of controls available (i) by Master Controllers (ii) by Drum/Cam type Controllers.
The Cabin controlled Crane will be controlled from Open/Closed Drivers Cabin by means of Master Controllers / Drum/Cam type Controller.
(B) Floor Operated Cranes.
The Floor controlled Crane will be controlled by means of Pendant Push Button Controller from floor.
(C) Radio Remote Controls.
The Radio Remote Controlled Crane will be controlled from floor by means of Hand Held type Radio Remote Control.
MOTORS :-
All Motors will be Totally Enclosed, 25% CDF / 40% CDF, High Torque, Crane Duty, Squirrel Cage / Slipring type, preferably in IEC frame Size. Motors will have generally Class B insulation suitable for tropical climate & high humidity. All Motors will confirm to IS:325. The Motors will confirm to details as given in quotations.
RESISTORS :-
Resistors when provided are designed as per BSS:587-1957 and are made of unbreakable grids formed from stainless steel or a similar alloy housed in a ventilated steel housing. These are suitable for intermittent duty having 5/10 minutes rating.
CONTROL PANEL :-
An electrical protective panel of sheet metal is provided, housing within it the following :-
1. Isolating Switch.
2. Push Button for stopping all the motions. This also acts as an Emergency stop.
3. Triple Pole Thermal Overload Relays for individual Motors.
4. One Contactor type Circuit Breaker.
5. One set of fuses for each Motor.
6. One Transformer for low Voltage supply.
7. One Set of Switch Fuses for Transformer protection.
8. Plug and Socket for connection to the hand lamp.
9. One indicating Lamp.
WIRING :-
All wiring between individual Motors, Controllers, Current Collectors and Resistance is with PVC armoured Cables, Control Wiring is done with PVC armoured Cables having Copper Conductors.
For the collection of current from the Driver’s Cabin to the Crab (Trolley), the most modern and safest arrangement of COBURN PULLEYS with Flexible Trailing Cables are provided.
For collection of current from the Down Shop Leads 4 numbers of Current Collectors are provided.
GENERAL :-
Testing :- The ELMECH Cranes are fully assembled & tested in our workshop before dispatch as per IS:3177. In this testing, all the motions are tried out in our works at load conditions. Cranes upto 30 Tonnes Capacity only can be tested at our works at Pune, for full load and overload as per IS:3177, prior to dispatch.
Load test and 25% overload test for the Cranes are performed at site if Erection and Commissioning of the Cranes are ordered on us. Arrangements for test loads for testing of the Cranes is purchaser’s responsibility.
Painting :- Before dispatch from our works, the structure is thoroughly scraped, cleaned and one coat of red lead paint applied. Machinery parts are finished with Enamel Paint. Exposed machined parts are Coated with Anti-Corrosive varnish.
OUTDOOR DUTY CRANES :-
In case the ELMECH Cranes quoted are for outdoor operation, in addition to the normal features as referred in the specifications, following points are taken care of :-
1. The structure of the Crane is made heavier to take into account wind pressures & corrosion allowance.
2. The Horse power of the Long Travel Motor is increased to account for the Wind pressure when the Crane is moving against it, as also the long travel machinery in general is made heavier.
3. Suitable Canopies are provided on all exposed parts to protect them against rain, etc.
4. The Driver’s Cabin is totally enclosed weather proof type.
EXPLOSION PROOF (HAZARDOUS) AREA CRANES (GAS GROUP IIA/IIB OR IIC) :-
In case of Explosion-proof Cranes, following Electrical items will have Explosion Proof enclosures :-
1. Motors.
2. Brakes.
3. Limit Switches – Explosion Proof Enclosure / Intrinsically Safe Circuit.
4. Pendant Push Button Station – Explosion Proof Enclosure / Intrinsically Safe Circuit.
5. Control Panel.
6. Hook – Hot Dip Galvanized considering Explosion Proof Area.
Wheels shall have Phosphor Bronze Lining to avoid Sparking.
If you have requirement of above Crane then kindly send following Technical details to eddycranes@vsnl.com to send our offer :-
1. Crane Capacity in Tonnes:
a. Main Hoist (MH):
b. Aux Hoist (AH):
2. Height of lift in Mtrs. for MH & AH/ Rail top from Floor Level:
3. Lift below floor level in Mtrs., if any:
4. Type of Crane:
a. Single Girder / Double Girder:
b. Underslung / Overhead
c. HOT/ EOT/ GOLIATH/ GANTRY/ GRABBING/ SPECIAL PURPOSE:
5. Exact Span in Mtrs. (Centre distance between rails/column):
6. Location of the Crane - INDOOR / UNDERSHED / OUTDOOR:
7. Area of classification: safe OR Hazardous,
If Hazardous then specify Gas Group, Temperature Class & Zone.
8. Duty as per IS-3177 (1999)/ IS-4137/ BSS 466/ DN 15018, DIN 15020/ Any other International Standard:
(M1/ M2/ M3/ M4/ M5/ M6/ M7/ M8) OR (Class I II or IV):
9. Length of Travel / Bay Length in Mtrs:
10. Desired speeds in all motion:
In Mtrs./min
a. Main Hoist:
b. Aux. Hoist:
c. Cross Travel:
d. Long Travel:
11. Do you need creep/Micro Speed in any of the Motion:
If yes, through conventional method (10 % of main speed through pony motor & planetary gearbox) or through latest VVVF drives technology (5% - 100% of main speed). Please specify:
12. Ambient Temperature in Celsius:
13. Operation: Floor Operated / Cabin Operated / Remote Control (RRC):
If Cabin operated, Open type or Closed type:
14. Type of material to be handled:
15. Required Power Feeding for DSL System (End/Centre/Two-end):
16. Painting Details:
17. Details of Lifting tackle / attachment, if required:
18. Any other relevant information if any, to suit your requirement:
19. Please send shop layout drawing indicating clearances available.
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