Two-blocking occurs when the operator extends the boom on a crane without letting out sufficient slack in the cable. As a result, the stabilizing weight, called the headache ball, will be popped off by the extending boom.
What does the term two blocking mean?
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 double blocking Crane?
A spotter should be available to direct the crane operator where there is the potential for double-blocking. Note: Double-blocking (sometimes known as two-blocking) happens when the hook block or headache ball makes contact with the head sheave(s) preventing further winding up of the hoist.
What are the parts of a crane called?
The Various Functions of Mobile Crane Parts
- The Driving Components. In any mobile crane, one of the common components will be the driving system used to make it mobile. …
- The Operator’s Cabin. The operator’s cabin houses all of the crane’s controls. …
- The Boom. …
- Hoist and Hook. …
- Hydraulic Pump. …
- Outriggers and Counterweights.
6 февр. 2020 г.
What is the end of a crane called?
JIB CRANE – A crane design whereby the bridge girder (commonly called the boom) is fixed at one end, allowing the opposite end to cantilever. The fixed end generally is hinged to allow rotation. LIFT – Maximum safe vertical distance through which the hook, magnet, or bucket can move.
What is the hook on a crane called?
A lifting hook is a device for grabbing and lifting loads by means of a device such as a hoist or crane. A lifting hook is usually equipped with a safety latch to prevent the disengagement of the lifting wire rope sling, chain or rope to which the load is attached.
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.
What is a block on a crane?
A Load Block is the assembly of hook, swivel, bearing, sheaves, pins and frame and is suspended by hoisting ropes or load chains. It is used to lift and move objects up to a specific lifting capacity.
Which types of limit switches are used in cranes and hoists?
Rotary geared type limit switches are suitable for use reversing drives such as hoists, winches, rolling mills and various other mechanisms used such used in steel plants such as coke oven and feeding machinery.
What is the difference between a crane and a hoist?
A Crane is a complex device used for moving loads in various directions. … While a hoist by itself can only raise and lower objects on a vertical plane, it is the component used for that purpose as part of a crane’s wider application. Hoists, as well as cranes, are typically used in a construction or industrial setting.
What stops the crane from falling over when it lifts something?
Why Don’t Tower Cranes Fall Over? This is mostly down to the concrete base, which is massive and needs to be poured weeks before the crane arrives. The triangulated cross-member structure of the mast gives it more stability and prevents bending. Plus, it’s anchored and bolted to the ground.
What are the three functions of a crane?
The main purpose of a crane is to lift extremely heavy amounts of weight. A typical crane is equipped with a hoist rope, wire ropes or chains and sheaves.
Modern day cranes are used for:
- Construction Materials.
- Railroad Tracks.
- Shipping Materials/Equipment.
- Scrap Metal.
- Mobile Homes.
5 нояб. 2015 г.
What is creep speed?
CREEP SPEED: A very slow, constant, continuous, fixed rate of motion of the hoist, trolley, or bridge: usually established at 1% to 10% of the normal full load speed.
How much does a crane cost?
Mobile Crane ($125,000 – $525,000+) – A common type of crane that is transportable, but may have limited range compared to the telescopic crane.
Why does the crane need to rotate?
Why does the crane need to rotate? … It has an input force or effort from the diagonal cables right at the top of the crane pulling the jib up, and a load pulling the jib down.