We use one to deliver a lot of our machines with.
If your looking at a power up and down trailer.
I would say a must for someone with a bad knee is to get one with a remote control.
The angle of the bed will make it difficult to get on and off any machine.
It is neat to be able to drive up on and with a key chain push the button and the trailer levels.
You will be glad you spent the extra TRUST ME![/quote]
On our 38' tilt semi trailer, (30' lower deck) the empty deck is tilted up & down by activating the hydraulic. A loaded deck will let itself down with the load by having a low pressure by-pass in the hydraulic system. Works very good for all of our equipment. The poor mans remote.

We have loaded 2 machines on our trailer before, it just takes 2 people at the same time to load and unload.