Banbury Lock is beginning to fail. It is only a matter before this beam lies horizontally on the floor. Lock beams by their very nature are out in the open 24/7/367. Once the grain starts to split, the rain gets in and the demise of the beam is just a matter of time, I have seen splits several inches deep, full of water, that could have been prevented with timely treatment. During the winter the sodden beams. fall prey to ice forcing the splits wider allowing more water in. I don’t think the beams ever really dry out.
Have you ever used Tetrion? Tetrion is a product that appears very much like Polyfilla. It can be used to fill all sorts of holes and cracks. Tetrion is slightly different to Polyfilla in that when it sets it is rock hard, So hard in fact that an angle grinder is required smooth it down, consequently when it is applied it is important to get a good finish before it dries.
I am sure if the rot in these cracks, when they were younger, were routed out and Tetrion applied and then properly painted, gate beams would last a lot longer than they currently do.
Hopefully now the CRT has stopped experimenting with with Beech wood and gone back to Oak we wont see to much water damage, but I doubt it. Maybe it time to opt for fabricated steel beams?