Kern-Liebers Ltd (Spiroflex Division)


We are  Manufacturers of Constant Force Springs including both constant force and variable rate extension springs, motor springs, constant force spring assemblies, brush springs & power springs.

Our extensive product range and bespoke manufacturing services
We offer our customers a range of standard products, many available from stock as well as bespoke solutions to meet specific requirements and applications.

The range of Spiroflex springs is considerable, from 2mm wide to over 100mm wide and a stock range from 0.05mm thickness to over 0.6mm thickness.

Our products are used in numerous industries, Automotive, White Goods, Aerospace, Defence, Point of Sales to name just a few. Our Quality Standards and systems have been developed to exceed the requirements of all these demanding industries.

Our springs are used for many functions, counterbalancing, feeding, retracting cables, clamping, power generation.

Constant Torque Motor Springs

Constructed from a specially stressed constant force spring, B-Motor springs provide high amounts of torque in a small package. These springs provide rotational energy from the torque output drum (D3), or linear motion with the use of a pulley, cable, or webbing.

Because there are a number of different B-Motor spring design solutions for a given application it is suggested that if a B-Motor spring outside our catalogue range is required that you consult with a Spiroflex engineer early in the design phase.

Please enter known information below, submit your information, this will create a B-Motor spring specification sheet for submission to Spiroflex.

Typical Applications
Power generation
Retracting cables
Drive mechanisms
Point of sale
Measurement of linear movement
Childrens Toys

Constant Force Extension Springs

Enormous extendibility of constant force in excess of 50 times the relaxed length can be achieved.

The original concept of constant force springs was Extension Springs for counterbalancing windows For many years this has been a perfect aid in the opening and closing of windows from residential applications to black taxi cabs through to Rolls Royce and Aston Martin cars.

Constant force extension springs provide a huge range of application opportunities. Springs can be can be mounted on a bobbin or bush or free running in a cavity or recess. Springs can be joined or laminated to provide increased force with minimal increases in space requirements.

Typical Applications
Point of purchase
Light counterbalances
Car door pillar adjusters
Shutter doors return
Cable clamps
Stapler feed mechanism
Industrial dryers
Vending machines

Spiroflex was founded in 1954 under the name "Tensator" and today we continue to specialise in the manufacture of constant force, constant torque, variable force, high start power springs and associated products to our own and our customers designs and requirements from many industries throughout the World.

Spiroflex invests heavily in engineering resources or both specialist product design as well as production techniques to provide flexible, efficient and cost effective support, designs and products.

We offer our customers a range of standard products, many available from stock as well as bespoke solutions to meet specific requirements and applications.

High Start Power Springs

Centrally winding, power springs offer high torque possibilities within confined spaces.

With springs ranges from 2mm in width and .05mm in thickness, Spiroflex represents the leading force in retraction systems, from inertia seatbelts and domestic vacuum cleaner cord retractors to dog leads and tape measures.

Almost all applications are bespoke; products are designed and developed in conjunction with our customers to suit the specific requirements of their application.

Spiroflex can supply products mounted into customers components, plastic housings or keeper rings, dependant upon design they can also be produced ‘pre wound’ to aid assembly on the customers production lines.

Typical Applications
Seat belts
Dog leads
Vacuum cleaners
Tape measures
Return mechanisms

EB-RW Maximum Energy Constant Torque Springs

Very high constant torque can be obtained by laminated R.W. springs through 90º angular movement.

A development from motor springs is the maximum energy torque spring or EB-RW. Essentially a short motor spring which generally consists of two or more spring laminations (up to 8 in each assembly) depending on the torque required and space limitations.

Typical Applications
Lever return
Door closures
Boot balances
Cash register/till lids
Loft doors
Pedal returns

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