The lifting hook block is a combination of the lifting hook and pulley block.
The crane hook blcok has two types: long and short.
The long hook blcok adopts the short hook blcok with the common hook handle and supports on the hook beam. The pulley is supported on the separate pulley shaft.
It has a high degree of height and reduces the effective lifting height.
The short hook block used to use long hooks, the pulley of which is directly mounted on the hook beam, which is reduced in height, but can only be used for double - rate pulley block.
Because the equilibrium wheel of the single multiplier pulley group is below, only the balanced pulley can be installed with the long hook block.
The short - shaped hook block produced now is similar to long hook block in the mechanism, but has short - type characteristics.
The short hook block can only be used for the smaller number of sliders.
When the multiplier is large, the number of the pulley group increases, the lifting hook beam is too long, so the bending moment is too large, and the lifting hook is too heavy.
So the short hook block only works for smaller cranes.
In order to be convenient for hoisting, the hook should be able to rotate the vertical axis at the horizontal axis.
Therefore, the hook is supported on the hook beam with thrust bearing, and the nut on the tail end of the hook is on this thrust bearing.
The nut should have a reliable anti-loose device, the thrust bearing should be dustproof.
In order for the hook to rotate around the horizontal axis, the shaft end of the long hook beam is made into a ring groove to match the shaft baffle, allowing the beam to rotate.
On the contrary, the axial end of the sliding axle is a flat notch, which does not permit the rotation of the pulley axis.
Pulley block and tackle group
The pulley block is composed of a number of pulleys, which can achieve the goal of both saving and changing the direction of force.
In use, the method of saving effort and rope is determined by the use of the pulley block.
The movable pulley is borne by two strings, namely, the force of the object and the movable pulley is one of the total weight of the object and the movable pulley.
Formula for calculating the force of the pulley block
Formula: s= hn.
V rope = n * n content
S: the distance from the free end of the rope.
H: the height of the weight is elevated.
N: the number of the weight of the rope.
The principle is: when n is odd, the rope starts from the movable pulley.
Use a movable pulley with three pieces of rope, and then add two pieces of string to each additional movable pulley.
If n= 5, two pulleys (3+2) are required.
When n is even, the rope starts from the fixed pulley, and all the pulleys are only used by two pieces of rope.
If n= 4, two movable pulley (2+2) is required.
Second, according to the requirement determine the number of fixed pulley, the principle is: general: two strands together with a movable pulley, a movable pulley usually with a fixed pulley.
When the force direction does not require a change, an even number of rope can reduce a fixed pulley.
You have to change the force
In the direction, we need to add a pulley.
To sum up, the design principle of pulley group can be summarized as: odd dynamic couple;
It's going to be a little bit, even a little bit, so it's going to be a plus.
Pulley: can rotate around the center axis fluted disc and across the soft rope of the disc (rope, tape, rope, chain, etc.) can be composed of the rotation around the center axis of simple mechanical parts processing.
The commonly used hand pull gourd in the factory is also a kind of pulley block.
The pulley block has been widely used in the processing of mechanical parts such as crane, hoist and lift.
There are two kinds of pulleys: fixed pulley and movable pulley, which can be combined into a pulley block, which can be both labor-saving and can change the direction of force.
Pulley block: a pulley block consisting of a fixed pulley and a movable pulley, which can be both labor-saving and changing the direction of the force.
The pulley group USES a few pieces of rope to hang the object, and the force used to lift the object is a fraction of the total weight.
The free end of the rope circumvents the calculation of the pulleys, and it doesn't count.
Although the use of the pulley block, it saves the force, but the distance is greater than the distance that the weight moves.
In order to both save and change the direction of power, the fixed pulley and the movable pulley can be combined into the pulley block.
It is easy to see that using the pulley block, although the use of the pulley block has saved the force, the distance from the dynamic movement is greater than the distance of the cargo.
The characteristics and functions of pulleys, movable pulley and pulley block
The fixed pulley can change the direction of the force, but it can't pull the object very easily.
Movable pulley can not change the direction of force, but can pull the object very much.
The pulley block combines the pulley and the pulley, which can change the direction of the force and save it
Pull the object in force.
The more you use the pulley in the pulley block, the more labor-saving it is.
The lifting hook block is the most common type of hoisting tool in lifting machinery parts.
The lifting hook block is usually suspended from the hoisting mechanism of the hoisting mechanism.
The hook block is divided into single hook and double hook.
The manufacturing method is divided into the forging hook group and the laminated hook group (plate hook).
Single hook manufacturing is simple and easy to use, but the force is not good. Most of it is used in the work of machining parts of machinery parts with weights of 80 tons or less;
The weight of the weight is often used in the double hook, commonly used in the 50-100t crane.
Folding plate hook block composed of several piece of cut steel plate riveted, individual crack of plate does not destroy the whole hook block and security is better, but the weight is bigger, mostly used in big lifting weight or lifting steel barrels of cranes.
The hook is often impacted during the operation, and it must be made of high quality carbon steel with good toughness.
The stacking hook is also divided into single hook and double hook, and the single hook is used on the crane with the weight of 37.5-175T, and the double hook is used to lift the crane with the weight above 100T.
The pulley in two places does not work the same.
The lifting arm head pulley is a transitional part of the pulley, basically not withstanding much force and not easy to wear, but sliding flexibly.
The pulley of the ear hook shall withstand a great amount of force, casting steel or forging steel better.