BLOCKSTEM is a P3 Thatcham-approved anti-theft advice for tractors and earth-moving machines, made from C4 steel with hardener, which is applied to the steering ram on full lock.

BLOCKSTEM is approved and endorsed by all major underwriters and by JCB Insurance, who offer up to 40% discount on premiums.

BLOCKSTEM is an innovative anti-theft device designed for vehicles with RAM operated steering. 

The lock is very easy to apply and can be in place in minutes.

It’s very simple. The device is placed round the RAM and locked into place with an individual key, specific to that lock only.

Because it is made of hardened steel, it’s impervious to mechanical attack.

BLOCKSTEM has been thoroughly tested, approved and accredited by Thatcham.

The theft of agriculture vehicles is increasing to the extent of over £1 million per week.  

BLOCKSTEM is a mechanical device.  It is not dependent on electronic systems that are increasingly vulnerable to sophisticated theft devices.

It also has the added economic advantage that the lock can be used on other machinery with the same dimensions.

Watch the video to see how to fit the lock to a tractor and to find out more.


50 mm Eye Lock for trailers

Derwent Lock and Security Ltd is the nominated distributor of Starcom Systems.

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  Contact details:​

 England  Scotland  Northern Ireland & Republic of Ireland
Derwent Lock and Security Ltd
Regis Rd
United Kingdom
Phone: 01902 744475 / 753842
Sellars Agricultural Ltd
Almondgrove Place
Inveralmond Industrial Estate
PH1 3TR    
Phone: 01738 620549
Glenview Farm Services
219A Battleford Road
Co. Tyrone
BT71 7NN
Phone: 0777 3417843
Visit the Derwent Lock & Security Ltd website