Trapped Key Interlocks | Industrial Safety Interlock Systems

Trapped Key Interlocking Systems

Haake Trapped Key Interlocks

Safety access systems require individual designs for the application - at ISS Safety, we use our broad range of components to create a bespoke interlocking system for your equipment.

Haake trapped key interlocks provide robust, reliable protection for industrial machinery and process safety. Made from durable stainless steel, they are easy to install and perform in harsh environments, resisting dirt, sand, snow, ice and moisture. The range includes bolt and access interlocks, power isolation switches, key exchange boxes, timers, and motion control sensors delivering secure isolation and controlled access across a wide variety of applications.

Product Features:

Accessible design drawings
Every key is individually coded and each lock only operatable by a predetermined code
No electrical integration - Haake trapped key interlocks can be installed purely mechanically
Maintenance free
Easy to retrofit
Poor weather and hostile environment resistance.

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STEP (ISO10303) files available on request

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Trapped Key Interlocks in Context

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Trapped Key Interlocks Products

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HST-TZ1 Single Key Slam Interlocks

The HST-TZ Door Interlock consists of a lock and slam-type locking catch mechanism. Inserting and trapping the key releases the catch, allowing the guard to open, while locking the guard is achieved by pushing it closed and turning the key. Single key units (HST-TZ1) are intended for part-body access. For flexible installation, the HST-TZ range is available in different housing orientations (left or right) with catch entry from either the front or rear. All components are manufactured from stainless steel and supplied with protective flip caps as standard.

HST-TZ2 Dual Key Slam Interlocks

The HST-TZ Door Interlock consists of a lock and slam-type locking catch mechanism. Inserting and trapping the key releases the catch, allowing the guard to open, while locking the guard is achieved by pushing it closed and turning the key. Dual key units (HST-TZ2) are used for full-body access when a personnel key is required. For flexible installation, the HST-TZ range is available in different housing orientations (left or right) with catch entry from either the front or rear. All components are manufactured from stainless steel and supplied with protective flip caps as standard.

HST-TS1 Single Key Access Interlocks

The HST-TS Access Interlock consists of a lock and locking bolt element and can be used on sliding or hinged doors. Single key units (HST-TS1) are intended for part-body access. For flexible installation, the HST-TS range is available in different housing orientations (left or right) and can be mounted using either front or rear fixings. The locking bolt element can be supplied with a chain if required. All components are manufactured from stainless steel and supplied with protective flip caps as standard.

HST-TS2 Dual Key Access Interlocks

The HST-TS Access Interlock consists of a lock and locking bolt element and can be used on sliding or hinged doors. Dual key units (HST-TS2) are used for full-body access when a personnel key is required. For flexible installation, the HST-TS range is available in different housing orientations (left or right) and can be mounted using either front or rear fixings. The locking bolt element can be supplied with a chain if required. All components are manufactured from stainless steel and supplied with protective flip caps as standard.

HST-S1 (Single Key Control Switches)rlocks

The HST-S range of switches is used for isolating machinery. Once voltage has been removed via a switch directly controlled by the key movement, the previously trapped key can be withdrawn and used to continue the interlocking sequence. While the key is released, the machine remains “OFF” and in a safe condition. HST-S units are available with multiple lock portions and a variety of isolation switches, in either cast aluminium housings or panel-mounted versions. All lock portions are manufactured from stainless steel and supplied with protective flip caps as standard.

HST-S2 (Dual Key Control Switches)

The HST-S range of switches is used for isolating machinery. Once voltage has been removed via a switch directly controlled by the key movement, the previously trapped key can be withdrawn and used to continue the interlocking sequence. While the key is released, the machine remains “OFF” and in a safe condition. HST-S units are available with multiple lock portions and a variety of isolation switches, in either cast aluminium housings or panel-mounted versions. All lock portions are manufactured from stainless steel and supplied with protective flip caps as standard.

HST-B Single and Dual Key Bolt Interlocks

The HST-B range is used to lock electrical switchgear—such as circuit breakers, disconnectors, and earthing devices—in the “ON” or “OFF” position by extending the bolt into a corresponding slot in a cam connected to the switchgear operating handle or toggle. The key can only be released when the switchgear is in the desired position. Variations include single or double key units, housing orientation (left or right), bolt length and diameter, front or rear fixings, and the option to fit a position limit switch for status indication. All components are manufactured from stainless steel and supplied with protective flip caps as standard.

HST-M Solenoid Released Control Switches

The HST-M range of solenoid-controlled trapped key interlock switches is designed to control access to machinery with run-down times or where a safety door is controlled by a Safety PLC. Power to the machine is isolated via a switch directly controlled by the key movement, which can only occur once a signal has energised the solenoid holding the key in place. Once the solenoid is energised, the trapped key can be withdrawn and used to continue the interlocking sequence. HST-M units are available with multiple lock portions, a variety of isolation switches, different solenoid voltages for access control, and in either cast aluminium housings or panel-mounted versions. All lock portions are manufactured from stainless steel and supplied with protective flip caps as standard.

HST-K System Key

Manufactured from stainless steel, the keys are uniquely coded to operate only with their designated lock, ensuring a high level of safety. Each key can be custom engraved with user-selected information, which is also displayed on the corresponding lock and its protective dust cap for clear identification.

HST-LS Switchgear Interlocks

The HST-LS Interlock is commonly used to lock electrical switchgear or control units in either the “ON” or “OFF” position. The standard unit features a 9.5 mm square × 48.5 mm long shaft that can be fitted with actuating levers or specific switchgear adaptors to operate motor or rotary-handled isolators. Turning the key moves the shaft through 90 degrees, isolating the supply and releasing the key. All components are manufactured from stainless steel and supplied with protective flip caps as standard.

HST-MTD Time Delay Units

The HST-MTD range of time delay units is designed to control access to machinery with run-down times. Under normal operation, secondary keys remain trapped in the unit and can only be released once a primary key is inserted and trapped. After the primary key is inserted, a pre-set timer runs down, allowing the secondary keys to be withdrawn. The primary key remains trapped until all secondary keys have been returned. HST-MTD units are available with varying run-down times and multiple lock portions. All lock portions are manufactured from stainless steel and supplied with protective flip caps as standard.

HST-WA Key Exchange Boxes

The HST-WA range of key exchange boxes is used to increase the number of keys available in an interlocking sequence. No secondary keys can be removed until all primary keys have been inserted and trapped, and primary keys remain trapped until all secondary keys are returned. HST-WA key exchange boxes are available in every combination of primary and secondary keys, making them ideal for larger interlocking sequences. All lock portions are manufactured from stainless steel and supplied with protective flip caps as standard.

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