Eot crane

07 Apr, 2016

EOT Crane OVERVIEW

EOT Cranes are industrial machines that are mainly used for materials movements in construction sites, production halls, assembly lines, storage areas, power stations and similar places. EOT Crane design features vary widely according to their major operational specifications such as: type of motion of the crane structure, weight and type of the load, location of the crane, geometric features, operating regimes and environmental conditions.

eot crane

Types of EOT crane

There are various types of overhead cranes with many being highly specialized, but the great majority of installations fall into one of three categories: a) Top running single girder bridge cranes, b) Top running double girder bridge cranes and c) Under-running single girder bridge cranes. Electric Overhead Traveling (EOT) Cranes come in various types:
1) single girder cranes - The crane consists of a single bridge girder supported on two end trucks. It has a trolley hoist mechanism that runs on the bottom flange of the bridge girder.
2) Double Girder Bridge Cranes - The crane consists of two bridge girders supported on two end trucks. The trolley runs on rails on the top of the bridge girders.
3) gantry cranes - These cranes are essentially the same as the regular overhead cranes except that the bridge for carrying the trolley or trolleys is rigidly supported on two or more legs running on fixed rails or other runway. These “legs” eliminate the supporting runway and column system and connect to end trucks which run on a rail either embedded in, or laid on top of, the floor.
4) Monorail - For some applications such as production assembly line or service line, only a trolley hoist is required. The hoisting mechanism is similar to a single girder crane with a difference that the crane doesn’t have a movable bridge and the hoisting trolley runs on a fixed girder. Monorail beams are usually I-beams (tapered beam flanges).

EOT Crane Working Principle

EOT Crane Working Principle system consists of three working movements: crane hook up and down lifting, trolley lateral movement and crane long traveling longitudinal motion.
Crane hook up and down lifting, trolley lateral movement and crane long traveling longitudinal motion Crane hook up and down lifting, trolley lateral movement and crane long traveling longitudinal motion

1.Transmission of hoisting system: the driving force of hoisting mechanism is from motor. It transmits power to the high speed shaft end of reducer by gear coupling, compensation shaft and brake-wheel coupling. Then through reducer to reduce the high revolution of motor to the required revolution, and output by low-speed shaft of reducer. The ring gear of drum transmit driving force to drum set, then through wire ropes and pulleys drive crane hook up and down, so as to finish the lifting of the heavy objects up and down.

2.Transmission of crane Trolley traveling system: the driving force of crane trolley is from motor. It transmits power to the high speed shaft end of reducer by brake-wheel coupling, compensation shaft and half gear coupling. Then through reducer to reduce the high revolution of motor to the required revolution, and output by low-speed shaft of reducer. And then by half gear coupling, compensation shaft, the half gear coupling joint with trolley driving wheels, so as to drive the trolley driving wheels rotating, so that finish trolley transport heavy objects by lateral movement.

3.Transmission of crane traveling system: the driving force of crane trolley is from motor. It transmits power to the high speed shaft end of reducer by brake-wheel coupling, compensation shaft and half gear coupling. Then through reducer to reduce the high revolution of motor to the required revolution, and output by low-speed shaft of reducer. And then by full gear coupling joint with crane driving wheel shaft, so as to drive the crane driving wheels rotating, so that finish bridge transport heavy objects by lateral movement.

Features of EOT cranes

Easy to install. Ensures maximum rigidity with a minimum dead weight
Compact dimensions, low weight, easy to operate and maintain
Safe and sustainable production at every level of our supply chain in compliance with ISO 9001 (Quality)
Product package also includes assistance with the installations, safety measures and training for operations and maintenance, as well as inspections and after sales services
Precision flat helical / spur gear units in light alloy housings with case-hardened gears, high- grade surface treatment and permanent oil / grease lubrication
Modular design, covering a very wide operating range. The systems are designed for ease of installation and maintenance and reliable operation, with fuse less circuitry, ducted wiring and non-screwed terminals. Each drive group is equipped with a motor overload protection
Safe and reliable hoisting and travelling
Higher efficiency to save power
Micro speed for all motions through inverter (VVVF) drives with suitable interlocking
Close loop circuit for hoisting mechanism with encoder feedback for fault detection
All motions are protected with limit switches to prevent over hoisting & over lowering of hook
Platform with hand railing for easy, simple & safe maintenance of the crane extended partially or totally along the girder width

ESSENTIAL PARAMETERS FOR SPECIFING EOT CRANES

To select correct crane envelope that will fit in the building foot print, the user must identify and pass on the following key information to the supplier:

Crane Capacity - The rated load, the crane will be required to lift. Rated load shall mean the maximum load for which a crane or individual hoist is designed and built by the manufacturer and shown on the equipment identification plate.
Lift Height - The rated lift means the distance between the upper and lower elevations of travel of the load block and arithmetically it is usually the distance between the beam and the floor, minus the height of the hoist. This dimension is critical in most applications as it determines the height of the runway from the floor and is dependent on the clear inside height of the building. Do not forget to include any slings or below the hook devices that would influence this value. Runway Height – The distance between the grade level and the top of the rail.
Clearance- The vertical distance between the grade level and the bottom of the crane girder.
Clear Span- Distance between columns across the width of the building. Building width is defined as the distance from outside of eave strut of one sidewall to outside of eave strut of the opposite

Side wall. Crane Span is the horizontal center distance between the rails of the runway on which the crane is to travel. Typically distance is approximate to 500mm less than the width of the building.

How much span a crane requires depends on the crane coverage width dictated by the application.

(According to the span and the maximum load handling capacity, the crane steel structure is selected to be either a single or Double Girder Crane construction).

Building Height- Building height is the eave height which usually is the distance from the bottom of the main frame column base plate to the top outer point of the eave strut. Eave height is the distance from the finished floor to the top outer point of the eave strut. There must be a safety distance between the top edge of the crane runway rail and the first obstacle edge in the building (for example roof beams, lights and pipes).
Runway Length- The longitudinal run of the runway rail parallel to the length of the building.
Hook approaches - Maximum hook approach is the distance from the wall to the nearest possible position of the hook. The smaller the distance is, the better can the floor area be utilized. Always check which crane gives optimum hook approaches and when combined with the true lift of the hoist you can utilize most of the available floor space. This is also termed as side hook approach.
End Approach – This term describes the minimum horizontal distance, parallel to the runway, between the outermost extremities of the crane and the centerline of the hook.
Bridge, Trolley and Lift Speeds - The rate at which the bridge or trolley travels or at which the hoist lifts is usually specified in feet per minute or FPM. The crane operating speeds are selected to allow safe operation whilst using the pendant. Dual operating speeds, normally a fast and slow speed with a ratio of 4:1 are commonly used but for optimum control a variable speed control system is strongly recommended.
Electrical Requirements - Specify the circuit voltage shall not exceed 600 volts for AC or DC current. Ideally 480 volt, 3 phase, 60 hertz for US requirements. The runway power is usually by conductor bar and hoisting trolley by festoon cable.
Control Requirements - The control circuit voltage at pendant pushbuttons shall not exceed 150 volts for AC and 300 volts for DC. Other control options including radio control, free-floating pendant (festooned) or hoist-mounted pendant requirements must be stated.

Eot Crane offering

Dongqi Crane has a comprehensive range of heavy duty EOT crane systems (double girder, single girder, underslung etc.) of capacity up to 500 tons for various applications in power, nuclear, shipbuilding, steel plant, heavy/general engineering sectors etc. We recommend you the perfect customized solutions after doing an in-depth analysis of your applications, production facility, factory, and material handling requirements.