Last revised: February 19, 2025

Keylock switches are activated by a key that is turned in a circle and can stop in a range of positions. These devices provide security for a switching function because they require a key to activate them and may have multiple positions they can turn to or simply turn to one position. Keylock switches are a type of rotary switch with the added security of a key.

A common application of a keylock switch is in a car ignition; the key can be used to start the car, or to turn the aux ignition (radio, lights) on. These devices are also found in industrial manufacturing equipment to prevent unauthorized use, or for safety reasons. For example, if an emergency stop switch is pressed it may require a keylock switch to be turned in order to reset the machine. Keylock switches may also be used for safety such as on the control box for blasting and demolition operations and on computers in place of additional passwords.

Types of Keylock Switches

Disk Tumbler

A disk tumbler (also spelled disc) is composed of slotted rotating detainer disks. A special key rotates the disks to align the slots and allow the sidebar to drop into the slots and open the lock. They do not use springs. Disk tumbler locks are better suited for areas with harsh conditions and are often used at outdoor locations like railroad and public utility installations.

Pin Tumbler

The pin tumbler is a locking mechanism that uses pins of various lengths to prevent the lock from opening without the correct key. It is commonly used in cylinder locks.

Wafer Tumbler

Wafer locks use a set of flat wafers to prevent the lock from opening without the proper key. It is composed of a single piece, but functions much like the pin tumbler lock.

Tubular Locks

Also known as a tubular pin tumbler lock, a tubular lock is a type of pin tumbler lock in which six to eight pins are arranged in a circular pattern and the corresponding key is tubular or cylindrical in shape.

Warded Locks

A ward lock uses a set of obstructions, or wards, to prevent the lock from opening without the correct key. These are mostly used in the UK and Ireland for internal and external doors and in America for inexpensive padlocks.

Double Sided and Single Sided Key

A double sided key has two sets of teeth, a standard upper level and a lower, less defined level. These are more difficult locks to pick than single sided keys which only have one set of teeth.

Specifications

Switches may have two or many contacts, may turn in one direction or two directions, may be momentary operation, or on off or some combination. The switching can be normally open or closed or change over.

Mechanical Life

Mechanical life represents the maximum life expectancy for keylock switches. Often, electrical life expectancy is less than mechanical life, so please consult the manufacturer.

Number of Poles

The number of poles is the number of separate circuits that can be activated at any given time. The term "pole" describes the number of separate circuits controlled by a switch; it is the input or common terminal. The number of circuits controlled determines the number of switch contacts, which in turn determines the poles needed to make or break the contacts. Switches typically have between one and four poles. The most common are a single pole (SP), a double pole (DP), or a triple pole switch (3P). Note that, in the image, the switch is connected to three separate circuits and has three contacts. For more information on poles and throws click here.

Angle Between Positions

Measured in degrees, the angular distance between positions determines the number of switch positions. For example, a 4-position rotary switch has a 90° angle of throw. For a 100-position rotary switch, the angle of throw is 3.6° degrees.

Number of Decks

The number of decks is the maximum number of decks that can be attached to a common, actuated shaft. They are also called a section, wafer, or module. There are two basic styles: single-deck and multi-deck. Each deck is a round plate with an arrangement of contacts. Single deck switches can control several circuits at a time. Multi-deck switches can control several circuits simultaneously. 

Number of Poles Per Deck

The number of poles per deck is the number of separate circuits that can be activated through a rotary switch per deck. The output connections are usually called ways instead of throws. The construction of the switch provides a total of 12 ways but there may be 1, 2, 3, or 4 poles. The rotating contact will channel the signal from the pole to the output terminals. The number of terminals required determines how many positions a switch will have.

Materials of construction for the base or housing and key or switch knob material of keylock switches includes metal and plastic.

Electrical Specifications

Important electrical specifications to consider when searching for keylock switches include maximum current rating, maximum AC voltage rating and maximum DC voltage rating.

To learn more about electrical specifications, material choices, and switch approvals please read IHS Engineering360's How to Select Rotary Switches selection guide.

Stop Style

Keylock switches with an adjustable or continuous stop are commonly available. The stop style should be selected based on the need of the application.

Adjustable stops give the user the option to stop when desired. Adjustable stops allow the user to take a 12-position switch and adjust it to have any number of positions between 2 and 12. This stop should be used for low volume requirements.

Fixed stops have the stop positions come fixed from the manufacturer and are not changeable by the user. They are better for volume production requirements so the user does not have to adjust the switch.

Contact Style

There are two basic contact styles for keylock switches: shorting and non-shorting.

• Shorting or make-before-break switches prevent arcing during position changing since the next position is connected before the previous position is disconnected. The contact is narrower.
• Non-shorting or break-before-make switches open the preceding circuit before closing the next. The contact is wider.

Features

Optional coded output — A switch with optional coded outputs can be configured to provide coded output, such as BCD or Octal.

Momentary ON — Momentary on is a feature in which the switch maintains its position for only as long as it is positively loaded or actuated; returns to unloaded position when it is let go (for example, an ignition switch).

Wiping contacts — Wiping contacts provide self-cleaning and usually low resistance. Wiping action creates mechanical wear.

Operating temperature — An important environmental parameter to consider when specifying keylock switches is the operating temperature. This is the full range of ambient temperatures the device can safely and accurately work in.

Keylock Switches FAQs

How do the specifications and contact styles of keylock switches impact their performance in different environments?

The specifications and contact styles of keylock switches significantly impact their performance in different environments. Here are some key points to consider:

Contact Styles

Shorting (Make-before-break): These switches connect the next position before disconnecting the previous one, which helps prevent arcing during position changes. This feature is particularly useful in environments where minimizing electrical noise and ensuring smooth transitions are critical.

Non-shorting (Break-before-make): These switches open the preceding circuit before closing the next, which can be beneficial in applications where it is important to ensure that circuits are not momentarily connected.

Specifications

Mechanical and Electrical Life: The mechanical life of a keylock switch represents its maximum life expectancy, while the electrical life is often less. This distinction is crucial in environments where switches are frequently operated, as it affects maintenance schedules and reliability.

Operating Temperature: The range of ambient temperatures a switch can safely operate in is a critical specification. In harsh environments, such as those with extreme temperatures, selecting a switch with an appropriate operating temperature range is essential to ensure performance and longevity.

IP Ratings: In environments exposed to dust, water, or other contaminants, IP-rated switches are recommended. For example, IP67-rated switches are dust-tight and protected against temporary immersion in water, making them suitable for harsh conditions.

Environmental Considerations

Harsh Environments: In industrial settings, switches may be exposed to contaminants, chemicals, and extreme conditions. IP-rated switches, possibly with additional protective measures like splash-proof boots, are advisable to maintain performance and safety.

Customization and User-Friendliness: In environments where operators may not be native English speakers, customizable symbols on switch caps can enhance usability. This feature is particularly important in global operations where clear communication of switch functions is necessary.

What are the differences between shorting and non-shorting contact styles?

The differences between shorting and non-shorting contact styles are as follows:

Shorting (Make-before-break) Contact Style

Functionality: In shorting contact style, the next position is connected before the previous position is disconnected. This ensures that there is no interruption in the circuit during the transition between positions.

Advantages: This style helps prevent arcing during position changes, which is beneficial in environments where minimizing electrical noise and ensuring smooth transitions are critical.

Contact Design: The contact is narrower, allowing for the overlap necessary to maintain connection during the transition.

Non-shorting (Break-before-make) Contact Style

Functionality: In non-shorting contact style, the preceding circuit is opened before the next one is closed. This ensures that circuits are not momentarily connected during the transition.

Advantages: This style is useful in applications where it is important to ensure that circuits are not momentarily connected, which can be crucial for preventing short circuits or unintended interactions between circuits.

Contact Design: The contact is wider, ensuring a clear break between connections.

What are the applications of keylock switches in different environment?

Keylock switches are versatile components used in various environments due to their secure and reliable operation. Here are some insights into their applications across different settings:

Industrial Environments

Harsh Conditions: Keylock switches are often used in industrial settings where they may be exposed to contaminants, chemicals, and extreme conditions. In such environments, IP-rated switches are recommended to maintain performance and safety. For instance, IP67-rated switches are dust-tight and protected against temporary immersion in water, making them suitable for harsh conditions.

Safety and Security: In environments where safety is a priority, keylock switches provide a secure method of operation, ensuring that only authorized personnel can activate machinery or systems.

Heavy-Duty and Off-Road Applications

Construction and Agriculture: Keylock switches are used in heavy-duty equipment such as construction machinery and farm vehicles. These switches are designed to withstand the rigors of such environments, including exposure to dust, water, and vibrations.

Customization and Visibility: In poorly lit environments, backlit switches with customizable symbols enhance usability and safety by providing clear visual indications of switch functions.

Medical Environments

Chemical Resistance: In medical settings, keylock switches must withstand exposure to sterilization chemicals. IP-rated switches with additional protective measures, such as splash-proof boots, are recommended to ensure reliability and longevity.

General Applications

Security and Access Control: Keylock switches are commonly used in applications requiring secure access control, such as in control panels and security systems. The key actuation ensures that only authorized users can operate the switch.

What are IP ratings and their significance in switch applications?

IP ratings, or Ingress Protection ratings, are crucial in determining the suitability of switches for various environments, particularly those that are harsh or demanding. Here's a detailed explanation of IP ratings and their significance in switch applications:

Understanding IP Ratings

The IP rating is part of the International Organization for Standardization’s (ISO) IEC60529 standard, which specifies the degree of protection provided by enclosures for electrical equipment against the ingress of solid foreign objects and liquids.

An IP rating typically consists of two digits. The first digit indicates the level of protection against solid objects, while the second digit indicates the level of protection against liquids.

Significance in Switch Applications

Protection Against Dust and Solids: The first digit of the IP rating ranges from 0 to 6, with higher numbers indicating better protection. For example, an IP6X rating means the switch is dust-tight, which is essential in environments with high levels of dust or particulate matter.

Protection Against Liquids: The second digit ranges from 0 to 9, with higher numbers indicating better protection against water ingress. For instance, an IP67 rating means the switch is protected against temporary immersion in water, making it suitable for environments where exposure to water is likely.

Application in Harsh Environments: In industrial and heavy-duty applications, IP-rated switches are preferred to ensure reliability and safety. They are designed to withstand exposure to dust, water, chemicals, and other contaminants, which are common in such settings.

Examples of IP Ratings

IP67: Dust-tight and protected against temporary immersion in water up to 1 meter. Suitable for outdoor and industrial applications where exposure to dust and water is a concern.

IP65: Dust-tight and protected against low-pressure water jets from any direction. This rating is often used in environments where the switch may be exposed to splashes or light rain.

What are the key specifications to consider when selecting a keylock switch?

When selecting a keylock switch, several key specifications should be considered to ensure it meets the requirements of the intended application. Here are the main specifications to focus on:

Contact Style

Shorting (Make-before-break): Connects the next position before disconnecting the previous one, preventing arcing during position changes. This is useful in applications where minimizing electrical noise is critical.

Non-shorting (Break-before-make): Opens the preceding circuit before closing the next, ensuring circuits are not momentarily connected, which is important for preventing short circuits.

Mechanical and Electrical Life

Mechanical Life: Represents the maximum life expectancy of the switch. It's important to consider this in environments where switches are frequently operated.

Electrical Life: Often less than mechanical life, so it's crucial to consult the manufacturer for specific details.

Operating Temperature

The range of ambient temperatures the switch can safely operate in is critical, especially in harsh environments with extreme temperatures.

IP Ratings

Indicates the level of protection against dust and water. For example, an IP67 rating means the switch is dust-tight and protected against temporary immersion in water, making it suitable for harsh conditions.

Actuator Specifications

Options include bare shaft, knobbed shaft, flush actuator, and keylock actuator. The choice depends on the security and tamper-proof requirements of the application.

Stop Style

Adjustable Stops: Allow customization of stop positions, suitable for low volume requirements.

Fixed Stops: Come pre-set from the manufacturer, ideal for volume production requirements.

Environmental Considerations

In environments exposed to contaminants, chemicals, or extreme conditions, additional protective measures like splash-proof boots may be necessary.

Keylock Switches Media Gallery

References

Electronics360—Design Considerations for Heavy Duty / Off-road Interior Switches

GlobalSpec—Rotary Switches Information

Image credits: 

Grayhill | Altech | Electroswitch