BW and Oxford Canal lift bridges - is there a catch?

Blogger Maffi has written about lift bridges on the Oxford many times, cataloguing the tale of Bridge 221 at Thrupp in particular. Here is just one of his posts.

This morning some "Advice" messages came from Waterscape. It seems that "catches" have been fitted to at least three lift bridges: 193, 233 and 234.

Oxford Canal

Wolvercote Lift Bridge 233

Monday 28 February 2011 until further notice

British Waterways have installed a catch mechanism on bridge 233, Wolvercote Lift Bridge to assist in the operation of the bridge.Users will require a BW Watermate key to operate with full instructions available on-site.

If you require any further information please do not hesitate to contact Jane Marriott, Project Manager on 01908 302563

I assume these catches are to keep the bridge in the open position. No doubt Maffi will provide a photo and his take on it on his blog.