How do they steer this?

I got the Gun Carriage finished finally. I have been working slowly on it over the last week and it was becoming a little bit of a chore. I painted it in two stages. The horses and undercarriage were the first to get done. I glued these into place without pinning them and now I am thinking I should have pinned them. I guess they will stay attached to the base. I was suprised by how much metal is in this kit. I would have thought the horses were resin too. At least assembly was simple, there aren't that many parts to work with and I only had to fill a few gaps on the horses.

I think the blending worked out for the most part especially with the large flat sides of the carriage. The weathering from the top and the wheels doesn't match 100% as they were painted separetely and I decided to experiment a little. I had wanted to put some dried mud on the wheels which would have covered a lot of the weathering but instead I wasn't brave enough and left them as is. The best mix for the mud I have found involves using plaster (spackle) and if I screwed it up it would be really difficult to remove. So rather than do this with an expensive model I think I will experiment a little more with some other cheaper model. The weathering on top is similar to that which I did on my watchtower. It isn't as textured as the wheels. I still think it looks fine.

So does anyone know how the crew manage to steer this thing?