TRIAL SI Patio Door Lock Drive Gearbox

Price £31.80 (Inc. VAT)
£26.50 (Ex. VAT)
(2 reviews) Write a Review
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TRIAL SI Patio Door Lock Drive Gearbox

Replacement gear box for Siegenia drive gears with the word TRIAL stamped on the side of the gearbox.

These locks are often found in:

  • Tilt and Slide Patio doors
  • Tilt and Turn Windows

The lock may have the name Sigenia or the letters SI stamped on to it.

The exact locking mechanism is no longer made so changing the centre gearbox is the only option left. This gear will be fixed by the screws provided and you may find that the old one may need drilling off but this is a very simple job for any person with DIY skills.


Video to follow soon.



SI trial Replacement gearbox


Please note that the replacement SI gearbox is fixed in the middle rotation position with a transit pin when you receive it. Once the replacement gearbox has been correctly installed into the door you will feel resistance for the first turn. Please be aware this is normal and once you apply a little force this will snap and the mechanism will be fully operational. (please note you don’t need to use excessive force as this would suggest it had been fitted incorrectly)


If you are unsure whether this is the right product for you then get in touch and we will do our best to help you
Call us on 01204 652211 or email

2 Reviews Hide Reviews Show Reviews

  • 5
    Marc Capper

    Posted by Marc Capper on Sep 03, 2019

    Marc Capper
    Easy to fit. Saved me a fortune buying a new door

  • 5
    Upvc lock gearbox

    Posted by David on Aug 21, 2019

    Absolutely thrilled. Better that the 25 year old original and a perfect fit. Considering the part was 'obsolete' it was well worth the search on the net. Excellent service. Thank you.