FAQ (Frequently Asked Questions)

Throughout history, humans have tried to build something for lifting and carrying heavy things. For example, equipment similar to modern jib cranes were made and used to build historical sites, e.g., Egyptian pyramids, to lift and place cube-shaped stones on each other. Components of cranes, before the invention of welding machines, were connected together by riveting. With increased knowledge, humans have been innovating and developing cranes for a variety of applications and operations. A piece of equipment called the hoist or winch is used for lifting the loads in all these different cranes. Hoists are categorized into two groups: wire rope winch and chain winch.

Wire rope is made of plaiting strands of steel wire, and it includes a central part known as the core around which the strands are twisted together helically. Each strand is also formed by twisting together a number of wires helically around the core wire.

The components of the wire rope are as follows:

Wires that are twisted together to form the strand

Strand is placed helically around the core

The core is the main part of the wire rope and is made of plant, synthetic, or steel fibre.

A gearbox is a machine used to transmit mechanical power from a power generating source to the consumer and satisfy the torque and rotational speed required by the consumer. In fact, the gearbox acts as an intermediary between the power source and power consumer that establishes a flexible relationship between the power source and power consumer.

In the wire rope hoists, it is considered a link between the hook and the wire rope body that is twisted together around the grooved drum. By rotation of the drum, the hook will move while remaining in the air, and the loading and unloading will be carried out. Due to the high verity of wire ropes and their arrangements, provision of wire rope hoists with high capacities (more than 1000 tons) and different hook heights (up to 150 meters) is possible. Only the electrical type of these hoists is only made.

Although the main components of wire rope winches are the same as chain winches, in the first case, wire rope is wrapped around the drum in rope winches and in the latter, a chain hoist is fed through hooks with safety catches. In fact, the chain winch is used for moving the objects by pulling the chains around the gears, and the chains are stored in the magazine after the operation is finished.

It is an electrical motor with a conical rotor that makes the easy transfer of the rotor on the safe activation axis of the brake easy by spiral spring being affected at the time of power outage. The speed of canned motors is an extensive combination of motor and gearbox that increases the scope of available objects and high speed of objects.

In addition to lifting travel, these winches are capable of moving the trolley along the girder and can provide 4 travel types for the user. These winches are used for building single girder cranes.

These winches lack the trolley and are placed by the hook on the trolley. One of the positive features of these winches is that assembling and disassembling can be carried out easily.

These winches lack the trolley and cannot travel along the girder. Therefore, they should be installed on the trolley. These winches only feature lifting travel and are used for manufacturing double-girder cranes.

This type of winch has a constant speed in lifting travel.

Double speed winch is used for lifting applications at low and high speeds. However, double speed winch is for both lifting and transverse travels at low and high speeds.

The working class of equipment for lifting and transferring the objects are based on the following indicators:

1. The working period of the equipment
2. Loading period of the equipment

The overall operation of the equipment is determined based on the total number of loading cycles in the normal life cycle of the equipment and is dependant on factors such as the number of working days, work shifts in a day, working hours per shift, and loading cycles per hour.

Equipment of ‘light duty’ class

-It refers to the equipment that is exposed rarely to maximum load.

Equipment of ‘medium duty’ class

-It refers to the equipment that is exposed now and then to maximum load.

Equipment of ‘very heavy duty’ class

-It refers to the equipment that is exposed almost always to maximum load.

The drums are equipment used to transmit force to wire rope which will be then transferred to the load to be lifted. In fact, it is one of the other components of the hoist for collecting the rope wire and is designed and manufactured with different diameters and lengths according to the latest world standards.

The wire rope guide is utilized in crane hoists. It is also used for placing the wire rope correctly on the drum while lifting the load.

A part of the winch that is located on the runways of girders of crane and moves the hoist along the bridge.

Load limiter in a crane that can measure the amount of load by measuring the consumed current of the engine. The crane users are aware that the damages resulted from lifting excessive load cannot be easily dealt with.

Problems resulted from a crane lifting excessive load can represent themselves as damages to physical structures, electric motors, and moving force of the crane. A crane is overloaded mostly when the user doesn’t have exact knowledge regarding the weight of the carried load. In most cases, there will be an excessive cost to compensate for carrying the excessive load.

If the weight of the current load is more than the allowable weight, the engine will draw a higher current. Then, the load limiter assesses the excessive consumed current and cuts off the current, if it was more than the allowable current (the consumption rate of the crane engine is directly proportional to the weight of the carried load).

The advantages of using the load limiter are as follows:

• Increased safety due to removal of excessive load
• Decreased cost of repair of crane structure and engine
• Increased efficiency caused by the lack of frequent repairs of crane engine and structure, and preventing downtime
• The increased life span of the equipment

The command switch is utilized to send commands to the crane components and parts. The number of bottoms on the command switch changes by a variation in the number of moving modes. In addition, command switches are different for single-speed and double-speed machines.

All the crane movements must be controlled, and their speed must reach zero if required. This component is used to control and stop the moving crane.

The wheel box is the moving mechanism of a crane and consists of frame, wheel, shaft, and accessories.

• The frame is made of ST37 sheet
• Wheels are made of cast iron GGG60 or steel MO40 and CK45 (mostly).
• The size of wheels depends on the crane capacity and can vary between 125 Ø and 620 Ø.
• ‘Driving’ wheel (figure. 1) will cause the structure to move with its build-in engine and the ‘driven’ wheel will loosely balance the structure.
• Flange connection of the wheel box, in addition to longitudinal rail alignment, provides a more balanced and flexible hoist movement. Also, it reduces damages induced in the wheel and railway.

It is a mechanical structure manufactured from ST37 plate with standard sections in boxes and coupled at the side to the girder flange using a flange. Alignment (or bonder) may be equipped with driving and driven gearboxes or wheels may themselves be placed in the bonder box. Length of the bonder box depends on the crane span, and its design and manufacture are performed according to DIN15018.