Magnets in Scalextric motors

Keeping the Scalextric motors at their best by keeping the magnet strong

Introduction

The electric motor in all Scalextric cars produced to date uses a 3 pole wire wound armature and a permanent magnetic field. Over the years 3 general types of magnet has been used, in the 1960 a ferrous (Iron based) block magnet was used then from the 1970s two shaped magnets have been used. More recently some high performance motors have been produced using the stronger shaped neodymium magnet.

This article relates to the earlier ferrous block magnet as fitted to the RX motor, Powersledge motor and the Formula Junior motor.

How a motor works

A motor works by having two magnetic fields attract / repel one another, just like two block magnets do. In a motor one magnetic field comes from the ferrous block magnet and one from the electrical current flowing in the wire windings. Therefore the stronger the magnetic field from the ferrous block magnet the more torque the motor will produce. The electric current is switched from winding to winding by the commutator as the armature rotates.

Magnetism

In any non magnetic ferrous material the spins of the electrons in the atoms of the material are randomised giving equal numbers of "up spin" and "down spin". It's the spin of the electrons that create the magnetic field. When the ferrous material is placed in a strong magnetic field the electrons all align so they spin in the same direction producing an overall magnetic field. The material has become magnetised.

However, the magnetised material is in a higher state of energy compared to non magnetic material. This means a ferrous block magnet will lose its magnetic effect when it can. To maintain the magnetic effect of a ferrous block magnet the magnet must be kept in a tight magnetic loop. This is why magnets when not being used use a "keeper". A "keeper" is a piece of magnetically conductive material that keeps the magnetic field in a fixed ferrous loop.

Magnets in motors

In a Scalextric motor the ferrous block magnet is kept in a tight magnetic loop using the steel motor frames and the ferrous core of the armature. In this way an assembled motor will retain its magnetism for many, many years. Each of the Scalextric motors that use the ferrous block magnet are magnetised as an assembled motor.

The problem with the Scalextric motors that use a ferrous block magnet is that if the magnet is removed from the motor, for any reason, it will immediately lose some of its magnetic field strength. Basic tests show that the magnet will be 20 to 30 percent weaker. There is no gain in magnetic field strength when the magnet is refitted to the motor. Do this enough times and the magnetic field will diminish to the point where the motor will not operate.

Conclusion

To maintain a healthy magnetic field strength the ferrous block magnet must be magnetised with the motor assembled. Specialists, like Scalextric Car Restorations, have the equipment to do this. Completely "dead" magnets can be brought back to life and the magnetic field can even be reversed in just a second. Reversing the magnetic field will change the direction of rotation of the motor.

Scalextric slot car parts Neodymium magnatraction magnet kit

Improved track performance with minimal effort.

These Scalextric spares Neodymium Iron Boron magnets have a gauss level which is typically 2 - 4 times higher than standard Alnico magnets. They are nickel-plated for improved corrosion resistance and appearance.

They are suitable for all slot cars; Artin, Ninco, SCX, Scalextric, SCX Scalextric, Tri-ang and many more.

This kit is great if you are not sure which Scalextric spares magnets would be best suited for your car. This kit contains:

Quantity	Description
2	Bar magnet 12mm x 6mm x 1.5mm (1/2" x 1/4" x 1/16" approx.)
2	Bar magnet 25mm x 6mm x 1.5mm (1" x 1/4" x 1/16" approx.)
1	Bar magnet 25mm x 6mm x 3mm (1/2" x 1/4" x 1/8" approx.)
2	Button magnet 8mm x 3mm (1/4" x 1/8" approx.)
2	Button magnet 8mm x 5mm (1/4" x 3/16" approx.)
1	Button magnet 10mm x 5mm (3/8" x 3/16" approx.)

Please see our Neodymium Magnet Safety Page for further information.

Our unique Magnet Downforce Calculator gives the magnetic attraction force for this magnet at given distances from the track. Ideal for locating the magnet.

Scalextric spares from Scalextric Car Restorations

Scalextric slot car Neodymium magnatraction magnet kit

Improved track performance with minimal effort.

These Scalextric spares Neodymium Iron Boron magnets have a gauss level which is typically 2 - 4 times higher than standard Alnico magnets. They are nickel-plated for improved corrosion resistance and appearance.

They are suitable for all slot cars; Artin, Ninco, SCX, Scalextric, SCX Scalextric, Tri-ang and many more.

This kit is great if you are not sure which Scalextric spares magnets would be best suited for your car.

 This kit contains:

Quantity	Description
2	Bar magnet 12mm x 6mm x 1.5mm (1/2" x 1/4" x 1/16" approx.)
2	Bar magnet 25mm x 6mm x 1.5mm (1" x 1/4" x 1/16" approx.)
1	Bar magnet 25mm x 6mm x 3mm (1/2" x 1/4" x 1/8" approx.)
2	Button magnet 8mm x 3mm (1/4" x 1/8" approx.)
2	Button magnet 8mm x 5mm (1/4" x 3/16" approx.)
1	Button magnet 10mm x 5mm (3/8" x 3/16" approx.)

Please see our Neodymium Magnet Safety Page for further information.

Our unique Magnet Downforce Calculator gives the magnetic attraction force for this magnet at given distances from the track. Ideal for locating the magnet.

Scalextroc spare parts from Scalextric Car Restorations.

Scalextric Magnatraction explained for your Scalextric cars

Introduction

Magnatraction is a made up marketing word from Scalextric (Hornby) to explain the use of a magnet to help give a scalextric car extra traction on the track. Simply put a magnet mounted to the chassis of a Scalextric car will be attracted to the steel track rails giving extra downforce and tyre grip. Hence the word Magnatraction

How does this work?

Magnets are attracted to steel and iron objects, this is well known. It is also well known that adding some weight over the rear axle of a scalextric car gives better traction. To explain this we need to take a look at a simple mathematical equation:
F = µ N

Where:

F = Force, this is equivalent to traction in our case.
µ = coefficient of friction, (pronounced mu). This is the interaction between the tyre material and the track material, tyre grip in this case.
N = Normal force, this is the force pulling the friction surfaces together.

This formula reads as:

"The traction the drive tyres give is equal to the grip of the tyre material to the track times the force the pulling the tyre to the track."
Therefore using weight over the rear axle or a magnet to attract to the track rails increases N and tyre grip is increased. Equally you can increase µ by using better, grippier tyres. That's it, maths states you can increase tyre grip by increasing µ and N.
Scalextric has selected the use of Neodymium magnets for all of their cars for some years and has become lazy over the tyre and track surfaces. They have massively increased N with the magnet and reduced µ to save time and money, lower grade tyre material and less grain on the track surface is the result.

Adjusting the grip levels

With the mathematical formula F = µ N there are only two variables to play with, µ and N. µ is all about the tyre and track surface while N is all about the downforce over the driving tyres. Lets consider µ.
µ has only a few options as you can change the track surface or the tyre material. Keeping your drive tyres clean and free of dust can be a great help and if this is not enough then MAX Grip tyres are available for all Scalextric cars. Apart from MAX Grip tyres the only other option is to change the track surface for more grip.
N, on the other hand, has lots of potential to tune the Scalextric car's performance. More magnets, stronger magnets is an easy way to give better grip. Less magnets, weaker magnets is an easy way to give less grip. One solution not always realised is the distance a magnet is from to the steel track rails controls the attractive force.
The Normal force from a magnet to the track rails varies as the inverse of the distance squared.

This means you only have to move the magnet a small amount to get a big effect. For example to reduce the Normal force from the magnet to one quarter the current value the distance between the magnet and the track rail just needs to be doubled. So, tuning the magnetic grip is relatively easy to carry out, stronger magnets for more grip and just move the magnet further away from the track for less grip.

Going "old school"

In this context "going old school" is all about removing the magnet completely and finding grip the old way. As we used to in the 1960s and 1970s before Scalextric hit on the idea of adding magnets. As F = µ N tells us, there's grippier tyres and weight to play with.
MAX Grip tyres and weight over the driving axle are the options available.

Conclusion

Magnatraction as used by Scalextric is a very easy way to give a Scalextric car significantly extra traction on the track. Strong Neodymium magnets can easily overcome poor mechanical grip from the tyres. With this feature the choice is a very personal one.
Magnatraction can be a great feature to speed up racing or it's a curse that reduces racing skill.

A great Scalextric article from Scalextric Car Restorations.

Scalextric slot car parts Neodymium magnatraction magnet kit

Transform your slot car's performance with these upgraded Neodymium magnatraction magnets.

Improved track performance with minimal effort.

These Scalextric spares Neodymium Iron Boron magnets have a gauss level which is typically 2 - 4 times higher than standard Alnico magnets. They are nickel-plated for improved corrosion resistance and appearance.

They are suitable for all slot cars; Artin, Ninco, SCX, Scalextric, SCX Scalextric, Tri-ang and many more.

This kit is great if you are not sure which Scalextric spares magnets would be best suited for your car. This kit contains:

Quantity	Description
2	Bar magnet 12mm x 6mm x 1.5mm (1/2" x 1/4" x 1/16" approx.)
2	Bar magnet 25mm x 6mm x 1.5mm (1" x 1/4" x 1/16" approx.)
1	Bar magnet 25mm x 6mm x 3mm (1/2" x 1/4" x 1/8" approx.)
2	Button magnet 8mm x 3mm (1/4" x 1/8" approx.)
2	Button magnet 8mm x 5mm (1/4" x 3/16" approx.)
1	Button magnet 10mm x 5mm (3/8" x 3/16" approx.)

Please see our Neodymium Magnet Safety Page for further information.

Our unique Magnet Downforce Calculator gives the magnetic attraction force for this magnet at given distances from the track. Ideal for locating the magnet.

Scalextric racing with Scalextric Car Restorations

Scalextric Magnatraction explained for your Scalextric cars

Magnatraction, how it works and how to adjust it for your for Scalextric cars

Introduction

Magnatraction is a made up marketing word from Scalextric (Hornby) to explain the use of a magnet to help give a scalextric car extra traction on the track. Simply put a magnet mounted to the chassis of a Scalextric car will be attracted to the steel track rails giving extra downforce and tyre grip. Hence the word Magnatraction

How does this work?

Magnets are attracted to steel and iron objects, this is well known. It is also well known that adding some weight over the rear axle of a scalextric car gives better traction. To explain this we need to take a look at a simple mathematical equation:
F = µ N
Where:
F = Force, this is equivalent to traction in our case.
µ = coefficient of friction, (pronounced mu). This is the interaction between the tyre material and the track material, tyre grip in this case.
N = Normal force, this is the force pulling the friction surfaces together.
This formula reads as:
"The traction the drive tyres give is equal to the grip of the tyre material to the track times the force the pulling the tyre to the track."
Therefore using weight over the rear axle or a magnet to attract to the track rails increases N and tyre grip is increased. Equally you can increase µ by using better, grippier tyres. That's it, maths states you can increase tyre grip by increasing µ and N.
Scalextric has selected the use of Neodymium magnets for all of their cars for some years and has become lazy over the tyre and track surfaces. They have massively increased N with the magnet and reduced µ to save time and money, lower grade tyre material and less grain on the track surface is the result.

Adjusting the grip levels

With the mathematical formula F = µ N there are only two variables to play with, µ and N. µ is all about the tyre and track surface while N is all about the downforce over the driving tyres. Lets consider µ.
µ has only a few options as you can change the track surface or the tyre material. Keeping your drive tyres clean and free of dust can be a great help and if this is not enough then MAX Grip tyres are available for all Scalextric cars. Apart from MAX Grip tyres the only other option is to change the track surface for more grip.
N, on the other hand, has lots of potential to tune the Scalextric car's performance. More magnets, stronger magnets is an easy way to give better grip. Less magnets, weaker magnets is an easy way to give less grip. One solution not always realised is the distance a magnet is from to the steel track rails controls the attractive force.
The Normal force from a magnet to the track rails varies as the inverse of the distance squared.

This means you only have to move the magnet a small amount to get a big effect. For example to reduce the Normal force from the magnet to one quarter the current value the distance between the magnet and the track rail just needs to be doubled. So, tuning the magnetic grip is relatively easy to carry out, stronger magnets for more grip and just move the magnet further away from the track for less grip.

Going "old school"

In this context "going old school" is all about removing the magnet completely and finding grip the old way. As we used to in the 1960s and 1970s before Scalextric hit on the idea of adding magnets. As F = µ N tells us, there's grippier tyres and weight to play with.
MAX Grip tyres and weight over the driving axle are the options available.

Conclusion

Magnatraction as used by Scalextric is a very easy way to give a Scalextric car significantly extra traction on the track. Strong Neodymium magnets can easily overcome poor mechanical grip from the tyres. With this feature the choice is a very personal one.
Magnatraction can be a great feature to speed up racing or it's a curse that reduces racing skill.

More great solutions from Scalextric Car Restorations

Scalextric slot car parts Neodymium magnatraction magnet kit

Transform your slot car’s performance with these upgraded Neodymium magnatraction magnets.  Improved track performance with minimal effort.

These Scalextric spares Neodymium Iron Boron magnets have a gauss level which is typically 2 – 4 times higher than standard Alnico magnets. They are nickel-plated for improved corrosion resistance and appearance.

They are suitable for all slot cars; Artin, Ninco, SCX, Scalextric, SCX Scalextric, Tri-ang and many more.

This kit is great if you are not sure which Scalextric spares magnets would be best suited for your car. This kit contains:

Quantity	Description
2	Bar magnet 12mm x 6mm x 1.5mm (1/2″ x 1/4″ x 1/16″ approx.)
2	Bar magnet 25mm x 6mm x 1.5mm (1″ x 1/4″ x 1/16″ approx.)
1	Bar magnet 25mm x 6mm x 3mm (1/2″ x 1/4″ x 1/8″ approx.)
2	Button magnet 8mm x 3mm (1/4″ x 1/8″ approx.)
2	Button magnet 8mm x 5mm (1/4″ x 3/16″ approx.)
1	Button magnet 10mm x 5mm (3/8″ x 3/16″ approx.)

Please see our Neodymium Magnet Safety Page for further information.

Our unique Magnet Downforce Calculator gives the magnetic attraction force for this magnet at given distances from the track. Ideal for locating the magnet.

A great selection from Scalextric Car Restorations

Scalextric Magnatraction magnet location

Fitting Magnatraction magnets to the older Scalextric cars can be difficult as the chassis was never designed to take a magnet.  Cars like the Formula 1 cars with the large Superslix tyres on the rear and full chassis plate are relatively easy as a flat plate magnet 1.5mm thick will fit between the motor and rear axle on the underside of the chassis.

 

Those cars that use the small Superslix tyres on the rear can be difficult as the chassis is too close to the track to fit a magnet on the underside of the chassis.  Also, there’s not really enough room to place a magnet on the inside of the chassis between the motor and rear axle.

On some cars the motor is angled up and away from the track.  If this angle is steep enough then a magnet can be secured to the underside of the motor.

Then there are the open chassis Scalextric cars.  With these you’ll be into fabrication to make a location to fit the magnet.

Knowing how close to the track rails to fit a magnet can be difficult too.  To help with this there is a magnet downforce calculator available.  This will help you work out the best location for the magnet on an old Scalextric car.

Another great insight from Scalextric Car Restorations

Scalextric Magnatraction magnet location

Fitting Magnatraction magnets to the older Scalextric cars can be difficult as the chassis was never designed to take a magnet.  Cars like the Formula 1 cars with the large Superslix tyres on the rear and full chassis plate are relatively easy as a flat plate magnet 1.5mm thick will fit between the motor and rear axle on the underside of the chassis.

 

Those cars that use the small Superslix tyres on the rear can be difficult as the chassis is too close to the track to fit a magnet on the underside of the chassis.  Also, there’s not really enough room to place a magnet on the inside of the chassis between the motor and rear axle.

On some cars the motor is angled up and away from the track.  If this angle is steep enough then a magnet can be secured to the underside of the motor.

Then there are the open chassis Scalextric cars.  With these you’ll be into fabrication to make a location to fit the magnet.

Knowing how close to the track rails to fit a magnet can be difficult too.  To help with this there is a magnet downforce calculator available.  This will help you work out the best location for the magnet on an old Scalextric car.

Another great insight from Scalextric Car Restorations