My toy hauler has a rear drop down queen bed like many toy haulers do. Mine uses a small piece of channel aluminum with a set of rollers that ride up and down in the channel aluminum. There is one channel on each wall of the toy hauler and the front of the bed glides up and down in the channel via the rollers, with the weight of the bed being supported and stabilized in motion by gas struts.
There are many toy haulers out there that use a nicer bracket on the bed with a huge roller that glides up and down in a monster sized steel c-channel that is usually powdercoated white and bolted to the wall. Generally there is also a bracket bolted to the wall with a rubber bump stop on it that acts as a small "shelf" to support the bed at each corner.
Here are some photos I took of the Fleetwood gearbox, which happens to have the setup described above:
I'm trying to find the names of companies that makes these things so I can upgrade my drop down bed to something more durable