{"id":12687,"date":"2020-01-10T09:45:14","date_gmt":"2020-01-10T14:45:14","guid":{"rendered":"https:\/\/blog.wika.com\/us\/\/?p=12687"},"modified":"2023-08-22T03:35:49","modified_gmt":"2023-08-22T08:35:49","slug":"limit-switches-for-cranes-winches-hoists","status":"publish","type":"post","link":"https:\/\/blog.wika.com\/us\/products\/force-products\/limit-switches-for-cranes-winches-hoists\/","title":{"rendered":"WIKA’s iSENS HES Limit Switch Offers Unsurpassed Anti-Two Blocking Technology"},"content":{"rendered":"

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. WIKA Mobile Control manufactures the iSENS HES limit switch that is ideal for this task.<\/strong><\/p>\n

Safety is paramount when operating heavy equipment. That\u2019s one reason WIKA acquired\u00a0WIKA Mobile Control<\/a> <\/span>(WMC), formerly known as Hirschmann MCS, to make sure customers have access to the marketplace\u2019s best safety systems for cranes and other mobile machines. One of those safety devices is a switch that prevents two blocking.<\/p>\n

What is two blocking?<\/h2>\n

An essential part of a mobile crane is the hoisting system that is used on the crane boom. This system is what enables the machine to lift and lower loads.\u00a0 <\/span>At the end of the boom are sheaves (grooved wheels), also known as the boom nose. The hoisting cable runs through the boom nose down to the hook block at the other end of the double pulley system. A large hook extends from the bottom of this hook block.<\/p>\n

A dangerous situation can occur when the hook block comes in contact with the boom nose pulleys; this is referred to as \u201ctwo blocking.” If this occurs, the impact could weaken or break the hoist rope, resulting in a dropped load and endangering the machine operator and any workers in the area. Unfortunately, two-blocking accidents have caused hundreds of deaths over the years.<\/p>\n

How to prevent two blocking<\/h2>\n\n
\"Anti-two

WIKA’s iSENS HES anti-two block (A2B) limit switch<\/p><\/div>\n \n

Careful operation helps to ensure that the boom nose and hook block sheaves do not come into contact with each other. A more sophisticated anti-two block (A2B) solution is the iSENS HES limit switch<\/strong>.<\/p>\n

As an A2B switch is a crucial safety mechanism, it must be extremely robust and reliable \u2013 able to withstand heat, cold, moisture, and dust. With ruggedness and flexibility in mind, WMC designed the iSENS HES anti-two block switch<\/a><\/span>.<\/p>\n

This switch has a corrosion-resistant housing, and all electronic functional parts are completely sealed. The 3-pole\/4-pole electrical connection cable comes in various lengths. The switching unit has an optional divisible operating weight and a ranging resistor for diagnostics to help monitor the integrity of the connection cable.<\/p>\n

The A2B switch by WMC operates reliably under a wide temperature range: from \u221213\u00b0F to +167\u00b0F (\u221225\u00b0C to +75\u00b0C). Built to withstand more than 1 million switching cycles, it has a very long mechanical lifespan.<\/p>\n

In addition, installation is easy. Simply attach a metal post to the boom tip, and then mount the switch to the post with a bracket. Chain connectors attach the counterweight to the actuating cable.<\/p>\n

The iSENS HES meets several important standards:<\/p>\n