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Crane lift height limit switches can be widely used in the control and limiting of three-dimensional space coordinates of lifting and transmission machinery in construction, ports, mining and other industries. The limit switches are composed of high-precision large transmission ratio reducers and mechanical synchronization with their output shafts. It is composed of a memory control mechanism and sensors. Because the WTAU series limit switch has the characteristics of small size, multiple functions, high precision, adjustable limit, strong versatility, and convenient maintenance, installation, use and adjustment, it should be extremely widely used in engineering machinery.
The limiter is a safety protection device used to limit the scope of each mechanism of the lifting machinery when operating. There are two types of limiters, one is the rising limit position limiter and the descending limit position limiter that protect the safe operation of the lifting mechanism; the other is the operating limit position limiter that limits the operating mechanism.
The rising limit position limiter is used to limit the lifting height of the fetching device. When the spreader is lifted to the rising limit position, the limiter can automatically cut off the power supply, stop the lifting mechanism, and prevent the lifting device such as hooks from lifting. Continue to rise, thereby preventing the lifting wire rope from breaking and preventing heavy objects from falling.
The lowering limit position limiter is used to limit the descending depth of the fetching device. When it reaches the lowest position, it can automatically cut off the power supply and stop the lifting mechanism from descending. At this time, ensure that the wire rope is wound around the drum with a remaining safety ring. No less than 2-3 turns (depending on the size of the roll).
Height limiter type
At present, the height limiting devices of lifting machinery that are widely used in the industry mainly include transmission type, weight type, flameout type and pressure plate type.
1. Transmission height limit device
The protection switch of the control circuit is activated through the transmission of the mechanical shaft. It is characterized by being directly connected to the drum, compact structure, high precision, easy adjustment, low failure rate, accurate action, and can set the lowering limit. It is the leading product on the market.
The limiter device consists of a worm gear reducer with a relatively large transmission, which is generally installed at the end of the reel shaft. The height limiter drives the worm and worm gear to rotate by the reel shaft, and the cam on the worm gear shaft also rotates accordingly, turning to a certain position. In the first position, the flange part of the cam contacts the limit switch, causing the limit switch to operate, cutting off the rising or falling power source, and stopping the spreader at the required position.
2. Heavy hammer height limiter
By touching the switch with a heavy hammer, the lifting control circuit is cut off and the action is realized. The weight-type height limiter has a simple structure and is the earliest height limiter used in lifting machinery. It is easy to install, especially in situations where it is not directly connected to the drum. However, there are also some defects in actual use. For example, the rope hammer is easy to get entangled with the lifting wire rope, causing parking failure; when the trolley is running, the rope hammer and the retrieval device are easy to swing, causing the protective action to fail.
3. Fire-off height limit device
The switch is connected in series to the main circuit of the power supply, and the action is achieved by breaking the live wire. When the lifting hook rises or falls to a certain limit position, it will push or pull the push-pull rod on the fire limiter, causing one pair of dynamic and static contacts to break, cutting off the main power supply, thereby playing a limiting role. When the push-pull lever and the action lever are reset, under the action of the spring force, the contacts are re-closed at the same time.
4. Pressure plate height limiter
The lifting mechanism control circuit is cut off through the linkage touch switch between the weight and the pressure plate. It is installed at the upper limit of the wire rope, and the rising hook pulley touches the switch support plate to drive the lower end to move out.
Please feel free to contactus Parts Sea engineers or sales for help if you have no parts No.
tse@partssea.com | sales@partssea.com
Crane lift height limit switches can be widely used in the control and limiting of three-dimensional space coordinates of lifting and transmission machinery in construction, ports, mining and other industries. The limit switches are composed of high-precision large transmission ratio reducers and mechanical synchronization with their output shafts. It is composed of a memory control mechanism and sensors. Because the WTAU series limit switch has the characteristics of small size, multiple functions, high precision, adjustable limit, strong versatility, and convenient maintenance, installation, use and adjustment, it should be extremely widely used in engineering machinery.
The limiter is a safety protection device used to limit the scope of each mechanism of the lifting machinery when operating. There are two types of limiters, one is the rising limit position limiter and the descending limit position limiter that protect the safe operation of the lifting mechanism; the other is the operating limit position limiter that limits the operating mechanism.
The rising limit position limiter is used to limit the lifting height of the fetching device. When the spreader is lifted to the rising limit position, the limiter can automatically cut off the power supply, stop the lifting mechanism, and prevent the lifting device such as hooks from lifting. Continue to rise, thereby preventing the lifting wire rope from breaking and preventing heavy objects from falling.
The lowering limit position limiter is used to limit the descending depth of the fetching device. When it reaches the lowest position, it can automatically cut off the power supply and stop the lifting mechanism from descending. At this time, ensure that the wire rope is wound around the drum with a remaining safety ring. No less than 2-3 turns (depending on the size of the roll).
Height limiter type
At present, the height limiting devices of lifting machinery that are widely used in the industry mainly include transmission type, weight type, flameout type and pressure plate type.
1. Transmission height limit device
The protection switch of the control circuit is activated through the transmission of the mechanical shaft. It is characterized by being directly connected to the drum, compact structure, high precision, easy adjustment, low failure rate, accurate action, and can set the lowering limit. It is the leading product on the market.
The limiter device consists of a worm gear reducer with a relatively large transmission, which is generally installed at the end of the reel shaft. The height limiter drives the worm and worm gear to rotate by the reel shaft, and the cam on the worm gear shaft also rotates accordingly, turning to a certain position. In the first position, the flange part of the cam contacts the limit switch, causing the limit switch to operate, cutting off the rising or falling power source, and stopping the spreader at the required position.
2. Heavy hammer height limiter
By touching the switch with a heavy hammer, the lifting control circuit is cut off and the action is realized. The weight-type height limiter has a simple structure and is the earliest height limiter used in lifting machinery. It is easy to install, especially in situations where it is not directly connected to the drum. However, there are also some defects in actual use. For example, the rope hammer is easy to get entangled with the lifting wire rope, causing parking failure; when the trolley is running, the rope hammer and the retrieval device are easy to swing, causing the protective action to fail.
3. Fire-off height limit device
The switch is connected in series to the main circuit of the power supply, and the action is achieved by breaking the live wire. When the lifting hook rises or falls to a certain limit position, it will push or pull the push-pull rod on the fire limiter, causing one pair of dynamic and static contacts to break, cutting off the main power supply, thereby playing a limiting role. When the push-pull lever and the action lever are reset, under the action of the spring force, the contacts are re-closed at the same time.
4. Pressure plate height limiter
The lifting mechanism control circuit is cut off through the linkage touch switch between the weight and the pressure plate. It is installed at the upper limit of the wire rope, and the rising hook pulley touches the switch support plate to drive the lower end to move out.