Disc-Lock Safety Wheel Nuts

Disc-Lock Safety Wheel Nuts

Disc-Lock Safety Wheel Nut
Disc-Lock Safety Wheel Nut Fleet Safety Award

What is the Disc-Lock Safety Wheel Nut?

The Disc-Lock Safety Wheel Nut is a free-spinning, vibration proof wheel nut, specifically designed to prevent wheel loss from commercial vehicles such as trucks, trailers and buses with spigot mounted wheel fixings. Disc-Lock Safety Wheel Nuts are considered to be far superior in terms of safety than standard two-piece wheel nuts. The combination of lateral bending forces on the road-wheels due to cornering and torsional forces due to braking and acceleration, which result in settling and looseness of normal bolted assemblies, cause Disc-Lock Safety Wheel Nuts to maintain the clamping force and to lock, thus keeping the wheels secure on the axle.

How does the Disc-Lock Safety Wheel Nut work?

Disc-Lock Safety Wheel NutUnlike a standard two-piece wheel nut, the Disc-Lock Safety Wheel Nut is split into three sections, comprising a nut (1), a hexagon-flanged washer (2) and a flat faced cup washer (3).   These sections are joined together to form a one-piece assembly with an O/ring.

The top two sections (1 & 2) have interlocking cams.  When subjected to road shock or vibration, the most common causes of wheel nut loosening, the interlocking cams of the Disc-Lock Safety Wheel Nut attempt to rise against each other.

How a Disc-Lock Safety Wheel Nut worksAs the angle of the cam is greater than the pitch angle of the thread on the stud a wedging action takes place and the Disc-Lock Safety Wheel Nut locks and will not come loose, thus maintaining the clamp load and keeping the wheel on the axle.

The Disc-Lock Safety Wheel Nut:

  • Maintains wheels on axles
  • Is approved by vehicle and axle manufacturers
  • Is fitted by major fleets worldwide
  • Is as simple to install as a standard two-piece wheel nut
  • Has MOD and NATO spec numbers

How good is the Disc-Lock Safety Wheel Nut?

Disc-Lock Safety Wheel Nut Junker Test

Safety Wheel Nuts are tested on a Junkers Vibration Test machine which is names after its German designer Gerhard Junker. Junker’s theories are based in part on the so-called “long-form torque equation” relating the torque applied to a fastener to the frictional and elastic reactions to the torque.

The Junker Test machine works as follows: an eccentric cam generates a controllable amount of transverse displacement on the joint under test. A load cell measures the actual transverse forces exerted on the joint. One can determine the relationship between residual preload in the fastener under test and external vibratory forces created by the test machine as a function of time.

When tested against a standard two-piece wheel nut on a Junker Test machine the Disc-Lock Safety Wheel Nut remains secure under the most severe vibration conditions while the standard two-piece wheel nut comes completely loose.

To find out more click play for a short video

 

 

MIRA logo Test Report

In December 2004 the Disc-Lock Safety Wheel Nut underwent a severe performance test at the Motor Industrial Research Association (MIRA) Proving Ground in Nuneaton, Warwickshire, UK.

A fully laden, semi-trailer/tractor-unit combination (weight 35 ton) was fitted with Disc-Lock Safety Wheel Nuts on the nearside and standard two-piece wheel nuts on the offside.

Over a two-day period the vehicle was driven around a figure-of-eight track to apply lateral bending movements to the wheels. In addition, repeated forward and rearward emergency braking was undertaken to induce torsional slipping forces to the wheels.  At the completion of each cycle of thirty minutes a torque check was undertaken.

These checks revealed no loss of torque on any of the Disc-Lock Safety Wheel Nuts at any stage.

The same could not be said of the standard two-piece wheel nuts, a staggering 50% of which had come loose by the end of the test.


Click here for a copy of the MIRA Test Report.

 

 

 

Safety Wheel Nuts 1

Safety Wheel Nuts 2

Disc-Lock Safety Wheel Nuts used by Sainsbury's

Disc-Lock Safety Wheel Nut Fleet Safety Award

Who uses the Disc-Lock Safety Wheel Nut?

The patented Disc-Lock Safety Wheel Nut is approved by vehicle and axle manufacturers throughout Europe and is fitted by many truck and bus fleets worldwide, who recognise the Nut as an essential safety device.

In addition, the product can also be used for a wide range of vibration purposes from railway points and crossings to cranes and conveyor belts.

 

What the experts say:

"The Disc-Lock nut should be encouraged and publicised because practical experience shows that it does make a major contribution to road safety and it is the most significant improvement to wheel security for years."
Eur Ing Don H Wright, Bsc (Eng), CEng, FI MechE

Disc-Lock Safety Wheel Nut
Disc-Lock Safety Wheel Nuts

Disc-Lock Safety Wheel Nut Fleet Safety Award

Disc-Lock Safety Wheel Nut Technical Specification

Disc-Lock Safety Wheel Nut Dimensional Chart

Size and Thread Width Across Flats Height Flange Diameter
A B C D
M18 x 1.5 34.0mm 29.0mm 47.5mm
M20 x 1.5 34.0mm 29.0mm 47.5mm
M20 x 2.5 34.0mm 29.0mm 47.5mm
M22 x 1.5 38.0mm 34.0mm 52.0mm

The Disc-Lock Safety Wheel Nut is manufactured from 1045 steel, heat treated to Rockwell C 32-36, and coated in GEOMET®, an environmentally friendly, anti-corrosion protection which is chrome free (compliant with European Union Directive 2002/95/EC (Restriction of Hazardous Substances).

The GEOMET® coating has passed a 720 salt spray test, far surpassing the industry standard of 96 hours.

The Disc-Lock Safety Wheel Nut received TÜV Approval No. 57 8703/01 in 1994 and TÜV Approval No. 76243829 in 2010

 

Disc-Lock Safety Wheel Nut Installation

Vehicles with 10 stud spigot mounted wheel fixings should be fitted as follows:

DAF, MAN, Volvo, Mercedes etc M22 x 1.5 RH - identified with 22-SA stamped on the nut face
Volvo (registered before September 2004) 7/8” – 14 UNF - identified with a 14 stamped on the nut face
All Trailers M22 x 1.5 RH - identified with 22-SA stamped on the nut face

Vehicles with 8 stud spigot mounted wheel fixings should be fitted as follows:

Generally all M20 x 1.5 identified by M20F stamped on the nut face.

Vehicles with 6 stud spigot mounted wheel fixings should be fitted as follows:

Generally all M18 x 1.5 identified with M18 stamped on the nut face.

Installation procedures and important maintenance points

Installation Figure A

 

Installation Figure B

Safety Wheel Nut Installation

  1. Check the nut and mating surfaces
    First check the inside of the socket is clean and free of debris and that wheel nuts and studs are clean and undamaged, particularly the threads. Also ensure all mating surfaces are clean and free of debris, paint and corrosion.
  2. Socket must be placed over entire wheel nut
    A deep six-point hex socket must be placed over the entire wheel nut. The socket must engage both top and bottom sections, when either installing or removing the Disc-Lock Safety Wheel Nut.
  3. Socket must not have a chamfer
    The socket should not have a chamfer on the inside as this may prevent it from engaging the bottom hex flange. See figure A.
  4. Lubrication
    It is essential to apply 2 drops of light engine oil to the last two or three threads at the end of each stud – this is important for maintaining the torque tension relationship as well as the life of the nut and stud threads, as per the Code of Practice for the selection and care of tyres and wheels for commercial vehicles issued by the British Standards Institution (BS AU 50: Part 2, Section 7a) recommendations.  Do not get lubricant on the mounting face of the wheel.
  5. Install in complete wheel sets
    Disc-Lock recommends that Disc-Lock Safety Wheel Nuts be installed in complete wheel sets ONLY.  (i.e. ten Disc-Lock Safety Wheel Nuts on a ten stud wheel or eight Disc-Lock Safety Wheel Nuts on an eight stud wheel.
  6. Nut Tightening Sequence
    It is recommended that the nuts are installed using the sequence as in figure B.
  7. Torque Settings
    Refer to the axle manufacturer’s instructions for torque settings.  However, Disc-Lock recommends its nuts be torqued to 700Nm (515 ft lbs) on M22 and 7.8” nuts in order to achieve optimum clamping force.
  8. Retorque your nuts
    It is critical that all wheel nuts are re-checked for tightness after 30 minutes, whether the vehicle has moved or not OR after the vehicle has travelled between 40 – 80 kms (25-30 miles).  This is to combat any settlement which may have taken place in the sandwich of the wheel fixing.
  9. Check ramp angle
    Before re-installing Disc-Lock Safety Wheel Nuts it is important to check that the ramp angle has not been damaged (i.e. flattened by excessive incorrect use of an air gun caused by not engaging the nut hex and the washer hex at the same time when removing the nut.)  Simply rotate the top section against the bottom section by hand to ensure the ramps have not been flattened.
  10. How to keep nuts in good condition
    To maintain Disc-Lock Safety Wheel Nuts in good condition and to prevent potential cracking caused by careless fitting methods or incorrect use of an air gun it is important to adhere to the following procedures:
  • Wheel nuts can be run up with a windy gun, but NOT UP TO TORQUE.  Be aware, guns without regulators can give well over 1200 Nm (900 ft lbs) of torque.
  • When using air guns it is important that the six-point hex socket of the air fun is placed over the entire Disc-Lock Safety Wheel Nut (both top and bottom hexes).  If this recommendation is not followed the air gun could damage the Disc-Lock Safety Wheel Nut by pulling it apart of crushing the rising cams.
  • Final turns and torque must be applied with a calibrated wrench.
  • If nuts must be removed, it is recommended they are undone with a bar first, not an air gun.

 

Don’t forget, it is critically important when fitting all wheel nuts to lubricate the stud.
Don’t have a proper socket or “L” bar?  Then call +44 (0)1978 668123 or e-mail Disc-Lock Europe info@disc-lock.co.uk and get one today.

 

 

 

Frequently Asked Questons - Disc-Lock Safety Wheel Nut

  • Who developed the Disc-Lock Safety Wheel Nut?
    The Disc-Lock principle was developed by Scotsman, Alistair McKinlay, in response to the growing problem of wheel loss from moving trucks, buses and trailers. Its revolutionary design has resulted in a safer and more reliable wheel nut than ever before and has been heralded as the most innovative development in wheel nut design since the 1930s.
  • Where are Disc-Lock Safety Wheel Nuts manufactured?
    Disc-Lock Safety Wheel Nuts are manufactured under license in Taiwan and Detroit, Michigan, USA.
  • How does the Disc-Lock Safety Wheel Nut Work?
    Unlike a standard two-piece wheel nut, the Disc-Lock Safety Wheel Nut is split into three sections, comprising a nut, a hexagon-flanged washer and a flat faced cup washer. These sections are joined together to form a one-piece assembly with an O/ring.

    The top two sections (the hexagon-flanged washer and the flat faced cup washer) have interlocking rising cams. When subject to road shock or vibration, the most common causes of wheel nut loosening, the interlocking cams of the Disc-Lock Safety Wheel Nut attempt to rise against each other. As the angle of the cams is greater than the pitch angle of the thread on the stud a wedging action takes place and the Disc-Lock Safety Wheel Nut locks and will not come loose, thus maintaining the clamp load and keeping the wheel on the axle.

    Click here for the Disc-Lock Safety Wheel Nut brochure.
  • What are the chances of losing a wheel if Disc-Lock Safety Wheel Nuts are fitted?
    The chances of ever losing a wheel from a moving commercial vehicle when fitted with Disc-Lock Safety Wheel Nuts, assuming the nuts have been fitted correctly and are in working order, are significantly reduced.
  • Can we fit half of the studs with Disc-Lock Safety Wheel Nuts and half with conventional wheel nuts?
    No, to ensure that the wheel remains secure Disc-Lock Safety Wheel Nuts must be used in full sets.
  • Which systems can be fitted with Disc-Lock Safety Wheel Nuts?
    All spigot-mounted systems can be fitted with Disc-Lock Safety Wheel Nuts. In fact, the Disc-Lock Safety Wheel Nut fits 90% of all commercial vehicles, trailers and buses, as well as most agricultural vehicles.
  • What about conical wheel systems?
    The Disc-Lock Safety Wheel Nut cannot be used on conical wheel systems or the DIN spherical system.
  • Can the Disc-Lock Safety Wheel Nut be re-used?
    Yes, the Disc-Lock Safety Wheel Nut can be re-used, but before refitting it should be inspected in the same way as one would inspect any wheel nut before reuse.
  • Does the Disc-Lock Safety Wheel Nut require a different torqueing to conventional wheel nuts?
    The Disc-Lock Safety Wheel Nut should be torqued to axle manufacturer's instructions for torque settings. However, Disc-Lock recommends its nuts are torqued to 700Nm (515ft lbs) on M22 and 7/8" nuts in order to achieve optimum clamping force.
  • Does the Disc-Lock Safety Wheel Nut maintain a 'torque tension' relationship?
    Yes, because of the special locking feature of the Disc-Lock Safety Wheel Nut it always maintains a 'torque tension' relationship.
  • What sizes of the Disc-Lock Safety Wheel Nut are available in Europe?
    Disc-Lock Safety Wheel Nuts are available in the following sizes: M18, M20, M22, 7/8" x 14 UNF and 7/8" x 11 BSF.
  • What material is the Disc-Lock Safety Wheel Nut made from?
    The Disc-Lock Safety Wheel Nut is manufactured from 1045 steel, heat treated to Rockwell C 28-32 and coated with Geomet®
  • Does the Disc-Lock Safety Wheel Nut have a special coating?
    Yes, the Disc-Lock Safety Wheel Nut is coated with an anti-corrosion coating – Geomet® – which has passed a 720 hours salt spray test.
  • Is the Disc-Lock Safety Wheel Nut corrosion resistant?
    Yes, the Disc-Lock Safety Wheel Nut exceeds industry standards for corrosion resistance.
  • Will the Disc-Lock Safety Wheel Nut operate effectively if painted in operator’s livery colours?
    No, the Disc-Lock Safety Wheel Nut will NOT operate effectively if painted, as paint can work itself between the two rising cam sections of the wheel nut thus rendering the unique locking design of the Disc-Lock Safety Wheel Nut ineffective. Disc-Lock Europe would strongly advise operators against painting wheel nuts.

    According to the Code of Practice for the selection and care of tyres and wheels for commercial vehicles issued by the British Standards Institution (BS AU 50: Part 2: Section 7a) "where wheel and hub surfaces mate they should be clean, free from surface protrusions and preferably free of paint."
  • How is the Disc-Lock Safety Wheel Nut fitted?
    An M22 Disc-Lock Safety Wheel Nut (most common size) is fitted with a six point M38 socket which must be placed over the entire wheel nut when fitting or removing. An instruction leaflet is provided with each order of Disc-Lock Safety Wheel Nuts or can be obtained from the Disc-Lock office free of charge (email info@disc-lock.co.uk) or download here.
  • Do you need to re-torque the Disc-Lock Safety Wheel Nuts after installation?
    Yes. This is very important. All wheel nuts require re-torqueing after approximately 80km/50 miles or 30 minutes standing time to ensure the torque tension relationship is maintained.
  • Do you need a torque wrench when fitting Disc-Lock Safety Wheel Nuts?
    Yes, when fitting any wheel nut a torque wrench should be used to check that the axle manufacturer's recommended torque settings are achieved (or Disc-Lock’s recommended torque of 700 Nm / 515 ft lbs).
  • Can an air-gun be used when fitting Disc-Lock Safety Wheel Nuts?
    The use of an air-gun when fitting wheel nuts is not recommended by the Institute of Road Transport Engineers. However, should an air-gun be used: "Final tightening (of wheel nuts) must be with a calibrated torque wrench set to the vehicle manufacturers' torque value. Air impact tools and extensions to wheel braces should not be used for final tightening." - IRTE Guide to wheel security. (Also see Code of Practice for the selection and care of tyres and wheels for commercial vehicles issued by the British Standards Institute, ref: BS AU 50: Part 2 - Section 7.)
  • Can an air-gun be used when removing Disc-Lock Safety Wheel Nuts?
    Yes, an air-gun can be used when removing the Disc-Lock Safety Wheel Nut, but it is essential to undo the nuts with a bar first. In addition, it is important to remember to place the air-gun socket over both hexes of the wheel nut. If the air gun is not placed over the entire Disc-Lock Safety Wheel Nut (both top and bottom sections) it could damage the nut by pulling it apart or grinding down the cams.
  • How can one maintain Disc-Lock Safety Wheel Nuts in good condition?
    To maintain Disc-Lock Safety Wheel Nuts in good condition and to prevent potential cracking caused by careless fitting methods or incorrect use of an air-gun it is important to follow the following procedures:
    a. Wheel nuts can be run up with a windy gun, but NOT UP TO TORQUE. Be aware, guns without regulators have been found which give well over 1200 Nm (900 ft lbs).
    b. When using air-guns it is important that the six-point hex socket of the air-gun is placed over the entire Disc-Lock Safety Wheel Nut (both top and bottom hexes). If this recommendation is not followed the air-gun could damage the Disc-Lock Safety Wheel Nut by pulling it apart or crushing the rising cams.
    c. Final turns and torque must be applied with a calibrated wrench.
    d. If nuts have to be removed, then they must be undone with a bar first, not with an air-gun.

    Click here for Disc-Lock Safety Wheel Nut Installation Guide which can be downloaded.
  • Should the wheel stud be lubricated with oil before fitting the Disc-Lock Safety Wheel nut?
    Yes, two drops of oil should always be added to the wheel stud before fitting the Disc-Lock Safety Wheel Nut. This not only prolongs the life of the threads, but also helps to achieve the proper torque tension relationship.
  • Does the Disc-Lock Safety Wheel Nut need a UK Vehicle Inspectorate (Department of Transport) Modification Certificate?
    No, the UK Vehicle Inspectorate has examined the Disc-Lock Safety Wheel Nut and stated in writing, dated 21st June 1994, that it does not require a notification certificate. (Copy of letter on request from Disc-Lock Europe).
  • Is the Disc-Lock Safety Wheel Nut acceptable for use on aluminium wheels?
    Yes, experience in the U.S. and Canada indicates no problem with galvanic corrosion between the Disc-Lock Safety Wheel Nut and alloy wheels. The Disc-Lock Safety Wheel Nut is fully approved in all sizes for use with alloy wheels providing the wheel nuts have been fitted correctly and the recommended torque has been applied.
  • Has the Disc-Lock Safety Wheel Nut a British Standard seal of approval?
    No, because the Disc-Lock Safety Wheel Nut is a unique product and is patented world-wide. There is no British Standard for this particular style of locking nut.
    The Disc-Lock Safety Wheel Nut received the German TÜV Approval - Certificate Number 57 8703/01 - which is recognised in Europe in 1994. (An English translation is available on application to the Disc-Lock Europe office.)
    The Disc-Lock Safety Wheel Nut was also endorsed by leading Lloyd's commercial motor insurer - the Crowe Insurance Group in 1997.
  • Will the fitting of Disc-Lock Safety Wheel Nuts affect axle manufacturers' warranties?
    No. As far as Disc-Lock Europe is aware axle manufacturers, including BPW, Gigant, GKN Dana, Granning UK, Hendrickson, Meritor ROR (formerly trading as Rockwell ROR) and SAF have inspected the Disc-Lock Safety Wheel Nut and have given no indication that the fitting of the wheel nut will affect their warranties.
  • Is the Disc-Lock Safety Wheel Nut patented world-wide?
    Yes, the Disc-Lock Safety Wheel Nut is patented world-wide in all metals.
  • How can I order Disc-Lock Safety Wheel Nuts?
    Contact Disc-Lock Europe. Telephone +44 (0) 1303 844762 E-mail: info@disc-lock.co.uk

Wheel Detachment

Bouncing Bomb 1Wheels which become detached from commercial vehicles and buses have been compared to bouncing bombs.  If a wheel becomes detached at high speed it can hit an oncoming vehicle or pedestrian with incredible force leading to serious accidents and sometimes fatalities.  Even at a low speed significant damage and injury can be inflicted.  And of course the detached wheel can also damage the vehicle as it comes loose or cause it to crash, causing further destruction.





Disc-Lock Europe Research

In 1992 Disc-Lock Europe commissioned the late Eur Ing D H Wright Bsc (Eng), CEng, FI Mech E, to undertake a survey into the level of wheel loss from commercial trucks and buses in the UK.  His findings revealed that around 2,000 to 3,000 wheel detachments occur each year, many of which went unreported, resulting in a range of minor to serious accidents each year in the UK.  He also estimated that between 5-10 people are killed each year and that each accident cost the insurance industry on average £26,500, or a staggering total of £53 million or more annually (1992 figures).


Department of Transport Report

Bouncing Bombs 3Wheel security for HGVs and buses has been a hot topic since the early 1990s and remains so today.  According to a Department of Transport report on Heavy Vehicle Wheel Detachment (issued August 2006), OEMs see loose/lost wheel fixings/wheel detachment as one of the most important vehicle safety issues, second only to collisions with other vehicles; while operators view wheel detachment as the leading vehicle safety issue.

In general, truck and bus operators want to fit the very best products money can buy to their fleets, especially when safety is in question and 45% of OEMs are reported as saying that wheel nut locking devices such as the Disc-Lock Safety Wheel Nut “are a good idea”.  So it’s not surprising to find that many leading truck and bus operators have tried, tested and now approve and fit Disc-Lock Safety Wheel Nuts as a matter of course.


Brake Logo Bouncing Bombs 4Read more about wheel loss on the Brake web site (the road safety charity) by clicking here

Disc-Lock Europe wins Brake Award

Brake Safety AwardBrake awarded Disc-Lock Europe a Fleet Safety Forum Award for Excellence for Vehicle Safety Invention in 2002 for its Disc-Lock Safety Wheel Nut and the work it had undertaken in highlighting the issue of wheel loss. The awards celebrate achievements and best practice in the field of risk management.

Mary Williams OBE, chief executive of Brake and the Fleet Safety Forum said:

"Disc-Lock Europe first entered the UK marketplace in 1991 with a product (the Disc-Lock Safety Wheel Nut) developed specifically as a solution to the dual problem of wheel nut loosening and wheel loss from trucks, trailers and buses. In 2003 the company introduced a new and improved product that, when independently tested on a Junker vibration test machine, always remained secure. In addition to manufacturing this safety nut, the winner of the award has also helped to raise awareness of the dangers of wheel loss by commissioning research and sponsoring a number of projects and information leaflets.”