MGB1: Coreless Motor and Crossed Helical Gearbox

£ 105.00 (Price excluding VAT £ 87.50)

This motor/gearbox combination offers the modeller several unique features, including the high power output of a coreless motor and the ability to ‘drive-back’ offered by crossed helical gears.

Manufacturer: Comet Models
Scale: 4mm - 00, EM, P4 etc.

1 in stock

SKU: MGB1 Category:


MGB1 is a powerful motor/gearbox combination that is suitable for use in large locomotives in 4mm scale. The motor is a 16mm diameter round can and so may not fit into narrow waisted fireboxes such as the Belpaire style found on Great Western locos such as the Castle and King. It will, however, fit in the firebox of LMS Princess and Coronation locos, and will also be ideal for locos such as the LNER A4 and W1 and for unrebuilt SR West Country/Battle of Britain and Merchant Navy locomotives.

For other prototypes the modeller is advised to check clearances carefully before committing to fitting the gearbox to the relevant chassis. In particular, the final drive gear in the gearbox has a diameter of approximately 16.5mm. After allowances for clearance over in-track features such as point crossings, that converts to a wheel diameter of approximately 5’0″ in 4mm scale and thus the MGB1 cannot be used for models of prototypes with a driving wheel diameter smaller than this. Also, the width of the gears used means that the overall width of the gearbox is 10.7mm. It will fit between the 00 frames of a Comet chassis, but may not fit other kit built locos.

Coreless motors need a smooth DC power supply. A feedback controller will make it ‘buzz’. If using it with a DCC chip then the CVs need setting to achieve that smooth supply. The current handling limit of the motor is 0.5A. The overall drive ratio is around 20:1.

Download instruction sheet

Additional Information

Weight 78 g