Hoist limit switch function Budgit Electric Hoists are equipped with either a paddle type limit switch, operated by the lower block in the up direction and an actuator attached to the chain in the lowering direction, or an electronic limit switch which relies on proximity switches mounted in the gear case cover. This article explores the function of limit switches and delves into the five essential safety limit devices found on tower cranes, providing guidance on selection and maintenance. All hoists are equipped with electronically programmable limit switches, which automatically stop the hook at any predetermined point when either hoisting or lowering. If the limit fails to stop lifting, be ready to press e-stop. Adjustable upper and lower limit switches regulate the load travel, and a chain-stop on the slack end of the chain serves as an extra measure of safety. When the hook block contacts the weight, which means a two-block condition is approaching, the hoist limit switch contacts open sending a signal that locks out the hoist up, boom up, and tele out functions. These devices monitor and control the motion of the crane, preventing accidents by halting operations when limits are exceeded. A variable-speed AC motor on the hoist drives the load up or down. Limit DO make sure hoist limit switches function properly. They Geared limit switches for wind turbines, cranes and winches Originally developed for limiting the end positions of overhead cranes or winches of crane hoists, gear limit switches have also been reprocessed and further developed for wind power applications. ). Operate pushbutton until near stop point and inch into stop limit both top and bottom. The fast-to-slow limit switch function prevents the buffer from travelling against the emergency limit switch at rated or double the rated speed. An overload clutch protects the unit from damaging overloads. Additionally, if a crane trolley travel limit switch is present, the operator should verify its proper operation in both directions prior to using the hoist. Limit switches are provided to protect the hoist against damage resulting from overtravel or to allow setting the hook travel within the factory-set limits of travel. 2. ab. In geared cam limit switches for Stromag AG, the many rotations of the shaft are translated into rotary angles of a cam disc. This switch may only be used during emergency situa-tions, and even then only by authorized personnel. Jun 15, 2022 · As an important element of overhead handling safety, upper limit switches are electro-mechanical devices used throughout crane, hoist, and monorail installations. Raise the load hook through all controller points stopping below the upper limit switch (where applicable); TABLE I-1 Troubleshooting for electric chain hoists, lever hoists and chain falls. Limit Switch for Tower Crane 1, Application of DXZ-Limit Switch for Tower Crane (hereinafter referred to as the limiter is a new type of safety protection device designed domestically， Suitable for AC 50HZ, voltage 250V and below, DC 30V and below control circuit, in the two-way control of three coordinates in space, arbitrary position, angle, stroke control and mold rubbing sensor control CWA hoist limit switches keep your stage safe, preventing costly damage and ensuring smooth theater operations. The counterweight (min. Jun 1, 2021 · Limit switches have practically limitless applications in regulating crane operation to prevent potential incidents. Limit Switches are used to detect the presence of objects, thus allowing the system to take desired action. Nov 11, 2021 · Cranes are one of the most valuable pieces of equipment in many industries, making it possible to lift heavy loads. What is the purpose of over hoist limit switch. Dec 11, 2019 · Hoist Upper Limit Controversy There is a huge controversy within the hoist inspection community when discussing the ANSI requirement of a secondary limit switch on European style hoists sold with only a single upper limit switch that is operated based upon drum turns. ) touches the upper block, boom tip 6 Inspection and maintenance 6. A weight is tripped by the hook block and tells the hoist when to stop raising. They can also be used to limit gate travel on locks, dams, intake water structures, or any moving item. Over hoist limit switch Jun 26, 2019 · The windmill position limit switch is commonly used in bridge cranes and gantry cranes (shown below), where the crane itself can traverse back and forth across the overhead beam. With the D-SH hoist you have purchased a product which offers various benefits: • Infinitely variable speed control, • Precise positioning, • Rocker switch and DSM Manulift with progressive characteristic, • Smooth load pick-up and deposit, • Smooth starting and braking, • Low-vibration operation, • Acceleration and braking ramps The standard limit switch is designed for lifts of 50 ft or less on single-chained hoists and 25 ft or less on the 2 ton, double-chained models. This protects the crane from mechanical damage and ensures loads are handled within safe limits. Inspection & Function of over hoist limit switch. Its primary role involves restricting the vertical movement of the load. To avoid such a potentially hazardous situation, THE OPERATOR SHALL: What are load limit switches? Dillon load limit switches are overload protection devices used to ensure that the capacities of cranes and hoists are not exceeded. When the limit switch level touches upper end, power supply to electrical motor gets stopped. Panel / gear limit switch Gear limit switch: The old standard for the hoist limit switch, was only an emergency limit switch, for up and down, that means two switches. Jan 2, 2025 · The Crucial Function of a Crane Limit Switch Limit switches are vital components in cranes, playing a critical role in ensuring safe and precise operations. A display mounted in the cab provides an audio and visual warning alarm when the crane's hoist block or hook gets too close to the boom tip. It is widely used on the CD MD type wire rope hoist of bridge cranes and gantry cranes. It acts as an automated “off switch” for the hoist motor in the vertical plane, preventing the load Limit switches are safety-relevant components used in crane systems to limit movements and monitor operation. Key Takeaway In an EOT (Electric Overhead Traveling) crane, the limit switch serves as a crucial safety and control device that prevents overtravel of the crane or hoist mechanism. With hoists that are equipped with an adjustable screw limit switch, the limit switch will automatically stop the hook at any predetermined point when either hoisting or lowering. Learn about Thern Stage Equipment's easy-to-install safety system. 13. The end positions of a crane lift correspond to rotary angles of the drive shaft. 5 kg) is used to pretension the hoist limit switch. Feb 8, 2025 · To mitigate risks and ensure safe operation, tower cranes are equipped with a range of sophisticated safety devices. Slew Limit Switch Usually provided in cranes, not provided with electrical rotary collector. This limit switch for crane hoist keeps the hook or load from rising too high or dropping too low. 2; Paragraph 2-1. Functions of Safety Device 1. Operation of the upper limit switch, on powered hoists, is one of the items the hoist operator must check during the daily inspection to be performed at the start of each shift, or at the time the hoist is first used during each shift. They ensure that the crane remains within the defined operating limits and thus prevent it from suffering mechanical or structural damage. These facilities have been selected on the basis of their demonstrated ability to handle all parts and repair When installed correctly, the A2B switch serves as positive break limit switch for use on winches, lifting equipment and cranes. Make sure hoist limit switches function properly. OPERATING INSTRUCTIONS Description ardened steel gears that also function as a brake. Types of position limit switches. It can be designed for other installations with a power reel or remote control. This is intended as a safety device and is not to be used on a routine basis to stop travel of lower block or shut off hoist. Here is your complete guide to understanding limit switches. For example, operators can receive real - time alerts if a limit switch is triggered, enabling them to take immediate action. Installed at the end of the crane’s runway or hoisting path, the limit switch gets activated when the trolley or hook reaches a predefined limit. However, the hoist should be tested by jogging the lower block against the limit weight to be sure the limit switch is functioning properly. Conclude this functional test by raising the hoist to check the limit switch and after putting into operation EVERY SHIFT. It checks the limit switch status and generates the Hoist limit switch. These switches detect when the crane or hoist reaches the end of its allowable range and signal the system to stop or adjust motion. Key Takeaway The purpose of a limit switch in an EOT (Electric Overhead Traveling) crane is to ensure safe and efficient operation by preventing overtravel. Geared limit switches are keeping track of the drum position, and have electrical contacts that open/close by adjustable cams to trip the switches at preset locations. Moreover, a limit switch keeps a crane from lifting loads above the appraised limit. Improper operation of a hoist can create a potentially hazardous situation which, if not avoided, could result in minor or moderate injury. Firstly, the Hoist Travel Limit Switch is located on the hoisting mechanism of the crane. Its main function is to prevent the crane from moving beyond its safe operating limits, such as over-lifting, over-lowering, or over-traveling in any direction. Operate pushbutton until near stop point and inch into stop limit, both top and bottom. The standard limit switch is designed for lifts of 50 ft or less on single-chained hoists and 25 ft or less on the 2 ton, double-chained models. An initial limit switch will slow the hoist before it reaches the stop limitation. These actuators strikes the contact finger of respective contacts Function: Limit Switch is to stop the mechanism of drive at the extreme clock wise / anti clock wise position. This crucial safety feature safeguards against over-travel, collision with obstacles, and potential damage to the crane or surrounding structures. Limit switches switch off automatically when a predetermined position is reached, for example the end of the lifting or lowering path. Don’t allow an operator to use the hoist until he or she has thoroughly read the manufacturer’s operating and maintenance instructions. Dillon load limit switches can have up to 4 microswitches installed on them to perform functions such IMPORTANT: Before placing hoist in operation, check the limit switch adjustment. Mar 12, 2021 · 1. Jun 29, 2022 · The gravity limit switches work with the help of gravity, hence they are often used for vertical movements such as crane hoists, electric hoists, main hoists of EOT cranes, auxiliary hoists of EOT cranes, hoist machinery and so on. Check the function of the limit switches. The switches ensure the safe stopping of the cranes cable (rope) operated limit switch. Final limit switches shall be set to function as close as possible to the terminal floors (the highest or lowest landing of lifts), without risk of accident. Another kind of limit switch prevents a hoist from reaching the upper block May 8, 2021 · The overload limit switch of the electric hoist is an important safety device to ensure the smooth progress of safe lifting work. Gear limit switch: ─ The gear limit switch serves as a hoist limiter in ABUS wire rope hoists at the highest and lowest hook position. Common problems include hoist will not lower, pendant will not work & more. The limit switch function (highest and lowest hook position) must be tested during start-up. Hoisting and loweringTrolley travelBridge travelLimit switches, locking and safety devices Hoisting and lowering Trolley travel Bridge travel Limit switches, locking and safety devices The trip setting of hoist limit switches shall be determined by tests with an empty hook traveling in increasing speeds up to the maximum speed. ” Originally in ANSI Z241. If either switch is not correct, adjust according to Importance of Crane Limit Switches Safety Assurance: The primary function of crane limit switches is to enhance safety by preventing the crane from exceeding predetermined limits. Crane limit switch is a device that is used to control and limit the motion of cranes and hoists. These load limit switches can be installed onto a hoist at the rope's dead end or equalizer sheave. When lower block lifts the limit weight, the hoist will automatically stop. Jun 11, 2025 · This hoist is known for its high efficiency and reliability. As illustrated in the hoist below, if the geared limit switch at UL2 failed to stop the hook, it would physically contact item # 6 which lifts a counterweight and in turn opens an electrical contact. Limit switches prevent the load block from colliding with the trolley. Limit switches are installed on each of the crane’s hoists as safety devices that set the precise travel range of the hoist. Dec 12, 2024 · Limit switches detect if the wire rope on the hoist drum is fully wound or unwound. The hoist limit switch on the SX2 through SX7 hoists is a rotary-type limit switch. This contact is wired into multi-function digital input (MFDI) S5 on Most limit switches like gravity, lever, and rotary limit switches find their applications in industrial cranes, hoists machinery, factories, etc. Traveling limit switch used both on crane and hoist or trolley. The limit switches play a key role in making sure that the hoist operates smoothly and safely in industrial settings. 3. It consists of a high-precision reducer with a large transmission ratio, a mechanical memory control mechanism synchronized with its output shaft, and a sensor. 2 mm) from bottom of the hoist on all units wi Functional Overview Functional Overview Functional Description The LimitSwitch function block is applicable to the following types of cranes: o Industrial Cranes (trolley, bridge and hoisting movement) o Construction Cranes (trolley, slewing and hoisting movement) The LimitSwitch function block reads limit switch inputs from the field. Application: A detailed video on how to adjust the geared hoist limits on the CM lodestar electric chain hoist. Jun 11, 2025 · In the context of hoists and trolleys, limit switches are used to control the movement of the equipment. This key-operated switch overrides control lever function switch-off by the LMI or by the hoist limit switch system. Introduction This ER2 electric chain hoist - high function series limit lock + lift-off/grounding impact attenuation unit is an exclusive kit for enhancing the functionality of the ER2 electric chain hoist. Suddenly, a critical oversight – the hoist mechanism doesn’t stop. A crane limit switch is a crucial safety feature of a crane that is used to limit the movement of the crane's load-bearing equipment. The limit lever is connected to a limit switch that automatically stops the hoist motor. DO maintain firm footing when operating hoist. OSHA does not require a backup hoist limit switch. Jul 25, 2025 · Crane hoist limit switches are crucial safety devices that protect loads and equipment by preventing over-travel during lifting and lowering operations. Gear-type limit switches for crane hoists S870 microswitches function as switching contacts in geared cam limit switches for Stromag AG. DO make sure that the hook latch, if used, is closed and not supporting any part of the load. Limit Switches Function: Controls the crane’s movement to prevent over-travel or overreach. 5 (D) requires a secondary upper hoist limit switch May 8, 2023 · FAQS How do limit switches work in an overhead crane? Limit switches detect when the hook or trolley reaches the end of its travel path and automatically shut off power to the crane motor. If either switch is not correct, adjust according to LIMIT SWITCH ADJUSTMENT, page 8. The function is reset automatically upon the next switching of the hoist limit switch. But do you know that one of the hazardous encounters in operating cranes is the occurrence of a two-blocking? So, what is two-blocking? Two blocking happens when the uppermost hoist line component (the load block, hook block, overhaul ball, etc. The action of the final limit switches shall be maintained whilst the buffers are compressed. These devices play a crucial role in ensuring safety, efficiency, and precision in a wide range of industrial applications. This is achieved by installing a two-block limit switch at the boom tip with a weight attached by a chain—the weight clamps around the hoist line above the hook block. It is designed to prevent the crane from overloading and causing damage to the crane or the load. The long lift limit switch allows for the maximum amount of lift, which is 143 ft on the 1 ton and under models, and 71 ft on the 2 ton models. Whether you are working with an overhead crane limit switch or other crane limit switch types, proper testing Manufacturer of Limit Switch - Hoist Limit Switch, Worm Drive Limit Switch, EOT Crane Rotary Gear Limit Switch and Eot Crane Limit Switch offered by Powerline Crane Systems Private Limited, Ahmedabad, Gujarat. 5. Mar 2, 2020 · Limit switches on hoist are safety devices that can cut power to certain functions of your hoist. The hoist is equipped with electronic overload protection, adjustable upper and lower limit switches, permanently lubricated and hardene There are several brake conditions monitored by limit switches which will each cause an emergency stop of the hoist: (1) brake wear, with a switch that monitors the thickness of the braking material; (2) broken links, with a switch that monitors the mechanical linkages on the brake mechanism, and (3) brake weights, with a switch that monitors Nov 29, 1993 · When the hoist is equipped with two upper hoist limit switches to prevent two-blocking, the first upper limit switch to be activated is the only upper hoist limit switch that needs to be tried at the beginning of each operator's shift. It enables you to use press button switches to easily set upper and lower limit lock positions and lift-off/grounding positions for the bottom hook based on the work, thus easing your work Retest the function by operating the hand controls The limit switches may need to be removed to fully inspect the wire condition The hoist has an oil filled gearbox equipped with alloy steel gears for smooth and durable operation. Mar 12, 2021 · The warning tag illustrated below in Figure 1-1 is supplied with each hoist shipped from the factory. X1 = Load hoist operation and limit switch test. A limit switch mounted to the cable drum sets the hoist’s lower limit preventing potential load and rig damage. For example, when ropes emerge from the groove or in keeping two trolleys from impacting on the same bridge structure. When applied to wire rope hoists, upper limit switches restrict their lifting motion at a certain point to prevent an accident. Applications of the EOT Limit Switch Limit Switches There are various types of limit switches employed in crane operations, each serving specific functions across different components of the crane's movement. Step # 3: Inspect Rope or Chain for Damage This system can be equipped with an external key-operated switch located in the crane op-erator's cab. With an inbuilt relay output to trigger a motion cut function, internal audible and visual operator warnings, clear LCD display, and low battery warning, the R147 is suited for those applications where Limit Switches are available for wire ropes of almost any size and for operation in the most severe environments. The invisible limit is set by driving the crane to the desired borderline, turning the dial on the Working Limits switch to the Set position and indicating which direction (s) the limit should point. Among these, limit switches play a vital role. Function of Crane Limit Switch The primary The anti two-blocking device consists of a weighted ring around the hoist line; the ring is suspended on a chain from a limit switch that is attached to the boom tip. Safety is paramount when operating heavy equipment. It also forbids the winding of the rope on the hoist drum in reverse direction during lowering 2. These rotary limit switches are particularly suited for use on reversing drives such as electric hoists, winches, over head cranes and traverse. Another type of limit switch keeps the hoist from reaching the upper block and rope drum Function of over hoist limit switch is to prevent the over run of the cradle and hitting the suspension mechanism. 8 Hoist limit switch 6. aa. Apr 1, 2025 · A rotating limit switch, also called a height limiter, manages the up-and-down motion of the hoist. In addition, a limit switch keeps a crane from lifting loads above rated capacity. Maximum care shall be exercised; the block shall be “inched” into the limit or run in at a low speed. Crane limit switch AFTER Crane limit switch BEFORE The limit switch is operated by contact with the crane hook block. These switches are in turn wired to the multi-function digital inputs of the drive or in series Limit Switch for EOT Cranes and Hoists Limit Switches are used in EOT Cranes to Limit its Movement for the purpose of safety. May 10, 2019 · The limit switch is a key piece of your crane that keeps it functioning. For instance, when ropes come out of groove or in preventing two trolleys from impacting on the same bridge structure. Page 16: Limit Switch 2. When activated, the limit switch interrupts power to the lift motor. Warn personnel of an approaching load. Jan 29, 2014 · A crane limit switch, or crane power limit switch, is a safety device designed to prevent the over-travel of a crane hoist. Dxz Hoist Limit Switch for Tower Crane 1/453 Multi-Function Load Limiter 1: 247, Find Details and Price about Multi-Function Switch Rotary Switch from Dxz Hoist Limit Switch for Tower Crane 1/453 Multi-Function Load Limiter 1: 247 - Jiangxi Nanma Electrical Co. May 21, 2024 · A limit switch is mounted on the deck of the trolley next to the equalizer or dead end. Wire Rope Hoist Load Limiters These load limiters can be added to almost all brands of hoists. The switch is mounted on the hoist gearbox and the drum gear turns the switch. Our limit switch accessories can be integrated with modern crane control systems. Trolley limit switch: Prevents the trolley from exceeding the allowable movement range. Metal shrieks, cables snap under CM HOIST PARTS AND SERVICES ARE AVAILABLE IN THE UNITED STATES AND IN CANADA As a CM Hoist user, you are assured of reliable repair and parts services through a network of Master Parts Depots and Service Centers that are strategically located in the United States and Canada. The switch-off points for the highest and lowest hook position are individually programmable using a teach-in button in the pendant control. The DXZ Series Multi-functional Limit Switch for Tower Crane is essential for tower cranes and other large lifting machinery equipment. Dec 9, 2024 · 6. This article will provide an overview of crane limit switches, including their function, types, and applications. Function of Upper and Lower Limit Switches on Construction Hoists Upper and lower limit switches on construction hoists are safety protection devices designed to control the height of the hoist during operation and ensure that the hoist automatically stops when it reaches the preset height. (i) At the beginning of each operator’s shift, the upper limit switch of each hoist shall be tried out under no load. As recommended by the Crane Manufacturers Association of America (CMAA) specification CMAA 78 – Standards and Guidelines for Professional Services Performed on Overhead Traveling Cranes and Associated Hoisting Limit switches are designed to prevent the hoist chain from over-traveling, which can occur if the hoist lifts too high or lowers too much. They can also be used as a load detection device by sending a signal to an alarm or light when reaching a specified load setting. The A2B Switch (Anti Two Block Switch/ Overhoist Switch) from the integrated Crane Safety Solution & Manufacturer- “Klug Avalon Pvt Ltd” based in India, is a This function serves to reduce the power requirement of the hoist limit switch. A must-have component in lifting machinery, the anti-two block limit switch helps the operator protect equipment, loads, and personnel by preventing the hook block from colliding with the boom. Extreme care shall be exercised; the block shall be "inched" into the limit or run in at slow speed. 1 The quantity and location of the chain components including cushion rubbers, chain springs and striker plates depend on the hoist model, capacity and limits switches. . This prevents over-spooling or complete unwinding, which could lead to hazardous situations. We appreciate your interest in employee safety and health. Slowing the hoist prior to reaching the limit decreases mechanical wear, as the hoist is traveling below maximum speed when the brakes set. Motion limiters for electric chain hoists Electronic hoist limiter The electronic hoist limit switch ensures additional operational safety with two freely selectable switch-off points. They're designed to stop the hoist or trolley from moving beyond a certain point, which helps prevent accidents and damage to the equipment. Under normal condition, the weight hammer is in free drooping state, the trigger lever extends outward, the limit switch closes, and the hoisting mechanism operates. Final limit switches shall operate before the car comes into contact with the buffers. All findings and reports should be kept on file for the lifetime of the equipment. Examples: Hoisting limit switch: Stops the hook from being raised too high. Before placing hoist in operation, check limit switch settings. This is also suitable as a regular limit stop with high switching precision. Crane Limit Switch The crane limit switch is a safety device which including traveling limit switch and load limit switch. Konecranes moves what matters | A leader in material handling Rayco Wylie SWITCH, A2B, WIRELESS FOR R147 ATB The R147 wireless over-hoist limit system (anti two-block) is an easy-to-install, cost-effective solution to monitor an over-hoist situation. Position limit switches can be used to indicate the relative position of the crane itself across the beam. DO make sure hoist limit switches function properly. When the "headache ball" or hook assembly touches the suspended weighted ring, the switch opens and an alarm in the cab warns the operator to stop hoisting. 1 Description of emergency hoist limit switch system (radio-controlled crane) The wire rope hoist is equipped as standard with an emergency limit switch for ↑ disconnecting in top and bottom hook position. 2 (a standard which has been discontinued) and now in ASTM (originally known as the American Society for Testing and Materials) there is a standard for molten metal hoists. ─ It has 3 switching points as standard, which can be used in the range of 92 rotations of the cable drum. It has the characteristics of small size, multiple functions, high precision, adjustable limit I. A magnetic disc brake delivers sure stopping and secure holding of the load. Sep 10, 2020 · To ensure both the safety and the optimal functionality of an overhead or gantry crane, it is critical to inspect a variety of components and operating functions at specific intervals. Rotary limit switches can be used for material handling on crane or winch drums, hoists, lifts, screw jacks, or platforms. The hoist limit switch which controls the upper limit of travel of “The hoist limit switch which controls the upper limit of travel of the load block shall never be used as an operating control. The standard limit switch is designed for lifts of 50 ft or less on single-chained hoists and 25 ft The upper limit switch is set at the factory to stop the hook block 3 inches (76. What is upper limit switch for hoist. Hoist Limit Switch Allows stopping hoisting movement, when the hook block approaches the trolley. Dec 5, 2024 · Limit switches are critical components in automation and control systems, used to detect the presence or absence of an object or to monitor the position of a mechanical part. 4. Aug 6, 2025 · over hoist limit switch time：2025-08-06 11:53:30 Click： 0 Over Hoist Limit Switch: The Silent Guardian Preventing Crane and Hoist Disasters Imagine the scene: A multi-ton load ascends smoothly towards its target height. Take up slack carefully - make sure load is balanced and load holding action is secure before continuing. Multi-Function Load Limiter 1: 247 Tower Crane Parts Hoist Limit Switch, Find Details and Price about Limit Switch Switch from Multi-Function Load Limiter 1: 247 Tower Crane Parts Hoist Limit Switch - Jiangxi Nanma Electrical Co. Before placing hoist in operation, check limit switch adjustment. Jan 26, 2024 · Hammer Height Limit Switch It can be used for electric hoist and crane winch trolley, and can only limit the height of rise. WIKA Mobile Control manufactures the iSENS HES limit switch that is ideal for this task. Beside our two metal housing limit switches series Alpha and Lambda we decided to create series Beta, which is made of fiber-reinforced thermoplastic material and offers the same robustness and in addition to that many new ideas for improvement. Be careful not to create a two-block condition by moving the hook slowly as it nears the upper limit. Without a reliable upper limit switch, the result can be catastrophic: wire rope failure The hoist limit switch is used on machinery and plants and especially on cranes, where a safe stop command needs to be triggered when the highest permitted position of the bottom crane flange is reached. The trolley carries the electric wire rope hoist that supports the load block and hook through a system of pulleys. If the switch does not operate properly, the appointed person shall be immediately notified. What happens if an overhead crane does not have limit switches? The Electronic Programmable Limit Switch function makes it possible to eliminate the geared limit switches (item #5 in Figure 1. The anti-two block switch (A2B) iSENS HES consists of a switching unit and an optional divisible operating weight. The anti-two-block switch(es) is (are) mounted at the head of the boom and boom extensions if available. The upper limit switch is set at the factory to stop the hook block 3 inches (76. hoist limit switches can be custom built to work with load limits, upper limits, and slack rope limits. Application: Rotary Geared Limit Switches are suitable for use on reversing drives such as Cranes, Hoists, Winches, Rolling Mills and various other mechanisms used in steel plants such as Cock Oven, Feeding Machinery etc. Feb 28, 2022 · Load tests should be dynamic, that is they confirm that the overhead crane and hoist function safely and properly as they move to lift and lower the test load, as well as transport it over the length of the bridge and of the runway. A crane limit switch is a safety device used in cranes and hoisting equipment to control the movement range of the crane’s lifting or travel mechanisms. If the tag is not attached to your hoist (for pendant control, the warning tag is attached to the pendant hose; for the pull cord control, the warning tag is attached to the up cord), order a tag from your dealer and install it. 2 mm) from bottom of the hoist on all units with standard 10 foot (3m) lift except Models AA and AA-2. By stopping the movement at the right time, they save Apr 1, 2025 · Discover the essential functions and types of crane limit switches. Its singular, vital purpose is to automatically interrupt the hoist motor’s upward or downward travel when the hook block (or load block) reaches a pre-determined upper or lower limit. DO make sure that load slings or other approved sling attachments are properly sized and seated in the hook saddle. They also find applications in Overhead cranes, Jib cranes, Electrical hoists, RTG Cranes, Single and double girder EOT Cranes, Traverser cranes, etc. Learn how they enhance safety, prevent overloads, and ensure smooth crane operations. All Load Limit Switches available in Stainless Steel by Request With hoists that are equipped with an adjustable screw limit switch, the limit switch will automatically stop the hook at any predetermined point when either hoisting or lowering. Easy Control for Crane Operators A working limit can easily be defined and removed by the overhead crane operator. The fast-to-slow limit switch function makes it possible to use one limit switch in each direction which results in an optimal C dimension. Although you may be familiar with this or similar equipment, it is strongly recommended that you read this manual before installing, operating or maintaining the product. , Ltd. Hoist limit switch At the beginning of each operator's shift, the upper limit switch of each hoist, shall be tried out under no load. Shut down a hoist that malfunctions or performs unusually and report such malfunction. In addition to safety, limit switches also contribute to the overall efficiency of the hoist and trolley system. These devices are engineered to stop the upward motion of the hook block and prevent “two-blocking”—a dangerous scenario where the hook block strikes the drum. 3 Limit switch A geared limit switch is built in as standard in the electric chain hoists. Jul 13, 2023 · Limiting switches are devices used in crane safety systems to detect and control the movement and positioning of crane components. At Rotor Cranes we custom manufacture load limit switches, rotary limit switches, and upper limit switches for wire rope hoists and chain hoists of any size and for operation in the most severe environments. The pull-wire switch (wire rope with ball available as an accessory) and the hoist limit switch must be mounted vertically. Heavy duty limit switches are used widely in cranes and hoists for position indication and over travel feedback. Acting as sensors, they make sure that cranes operate within predetermined limits to prevent accidents and limit damage caused by triggering actions. The new designed cross limit switch Beta is based on long-term experience in the crane and hoist market. NEMA special application limit switches 9007CLS1, 9007WC1 hoist overtravel limit switch Cross-type limit switch ABUS cross-type limit switch for electric limitation cause the automatic reduction or switching off of the travel movement of cranes and trolleys. Alternatively, the gear limit switch can be delivered with 137, 190 and 280 rotations for larger hook paths and for use with ABUCompact chain hoists A redundant secondary Upper Limit Switch (separate hardware) is required in case of failure of the primary upper limit stop. While these switches are critical safety features, they are not intended for regular use as stop mechanisms. If the switch does not operate correctly, the appointed person shall be promptly notified. Whether used in manufacturing, robotics, or heavy machinery, limit switches help control machine Jun 10, 2021 · Don’t operate a damaged, malfunctioning, or unusually performing hoist. The load limit switch can be installed onto a hoist at the rope's dead end or equalizer sheave. See specific crane limit switch applications here. Oct 15, 2024 · If that limit switch is not there, that could cause damage to the clutch mechanism,” said Weber. That’s one reason WIKA acquired WIKA Mobile Control (WMC Parts - Limit Switches Rotor Cranes Mar 14, 2025 · Understanding Upper Limit Switches in Wire Rope Hoists Upper limit switches are a critical safety component in any wire rope hoist system. The installation of upper and lower limit switches can prevent the hoist from overrunning or e upper limit switch stops the upward motion. 1 Terms and Summary This manual provides important information for personnel involved with the installation, operation and maintenance of this product. Don’t use limit switches as a routine method to stop load movement; this will cause premature wear of the components. The hook crashes violently into the hoist drum assembly above. Actual pictures of the electric hoist overload limit switch Working principle and installation method The switch is a kind of switch device that realizes the internal contact on Aug 4, 2025 · At its core, a hoist limit switch is a safety device integrated into a crane’s hoisting mechanism. Within our product range we offer the world renowned CM lod Check the function of the limit switches. A limit switch is an electro-mechanical device used to send an electrical signal based on a physical interaction. American National Standards Institute ANSI standard B30. Apr 14, 2022 · Limit switches have boundless applications in managing crane activity to prevent potential occurrences. This allows for remote monitoring and control of the limit switches, enhancing the overall efficiency of crane operations. 8. The Take up slack carefully - make sure load is balanced and load holding action is secure before continuing.