An anti-two-blocking system is a technologically advanced electrical device with a built-in sensor that helps the crane operator prevent two-blocking incidents. Two of the most popular variations of this safety device are wireless ATB systems and hardwired ATB systems.
What is anti two block device in Crane?
Anti two-blocking devices are electrical sensing devices. They are installed on the crane to prevent the “headache ball” from hitting the sheave. If such contact causes the line to break, the man basket can tip or fall. … Currently, most new mobile hydraulic cranes are equipped with these devices.
What 2 block means?
Filters. Of or pertaining to being prevented from proceeding. From nautical terminology for a ship’s rigging or crane rigging in which two blocks are locked together, stopping the line.
What is LMI in Crane?
Load Moment Indicator – LMI
For hydraulic cranes, the LMI reads its load value using a pair of pressure transducers, which read the cylinder pressures of the lift cylinders. An advantage of an LMI is the weight of the boom is calculated as a part of the load calculation.
What is limit switch in Crane?
Limit switches are electromechanical devices that regulate everything from household appliances to industrial machinery. For an overhead crane, they provide solid, established points of reference for maintaining efficiency, reliability and safety standards.
Which two cranes use a lattice boom?
There are three types of lattice boom cranes.
- The crawler crane has the advantage of moving with loads for a short distance. Its maximum capacity is 1.600T. …
- The outrigger crane consists of the pedestal crane and the truck crane. …
- The third type is the ring crane.
How many minutes is 2 blocks?
In Manhattan, there are about 20 north-south blocks to a mile, so 2 blocks is about 1/10 of a mile or about 1/5 km. East west blocks – well, they vary. Mostly it’s about 7 to the mile but some are shorter.
What does a block away mean?
A block is the distance on a street between one cross street and the next cross street. Away means not here. A couple of blocks away means not very far from here. … That is, the area is divided into blocks. The blocks may be separated by roads or lanes.
What is LMI in safety?
The LMI-system (Load Moment Indicator) is an important part of the crane. It measures the loading moment and prevents overloading. The LMI-system protects the crane, crane operator and bystanders against unsafe situations.
What is SWL in lifting?
All lifting equipment, including accessories, must be clearly marked to indicate their ‘safe working loads’ (SWL) – the maximum load the equipment can safely lift.
How is crane load capacity calculated?
Crane Lifting Capacity Calculation
(r)(hC)/100, where r is the radius (distance along the ground to the load) and hC is lifting height times capacity. Capacity, in turn, is particular to each boom arm length and angle chosen, and must be looked up in a table such as the one in the Resources.
Why is the limit switch important?
The limit switch then regulates the electrical circuit that controls the machine and its moving parts. These switches can be used as pilot devices for magnetic starter control circuits, allowing them to start, stop, slow down, or accelerate the functions of an electric motor.
What is the purpose of a limit switch?
A limit switch is an electromechanical device operated by a physical force applied to it by an object. Limit switches are used to detect the presence or absence of an object. These switches were originally used to define the limit of travel of an object, and as a result, they were named Limit Switch.
What is over hoist limit switch?
Over hoist limit switch is a safety device that is provided to allow the setting of the hoist travel within a prescribed travel range. Hoist: The upper limit of hoist travel is achieved through a hook operated type limit switch and the lower limit of hoist travel is achieved through a drum-activated limit switch.