Other than the normal brake caliper cylinder where you ‘squeeze’ them to return them , are there other types and what method is used to return them into the body of the caliper ?
c-clamp and old brake pad will do it.
There are different methods to get the piston back in the bore.
On most front brake calipers you just have to squeeze the piston back in.
On systems that use rear disc brakes there can be a number of different ways to get the piston back. Some have to be threaded or screwed back in. I’ve seen some where there is a allen set screw that has to be turned to allow the piston back.
If the parking brake is part of the caliper, the piston may have to be rotated to get it to retract. In ALL cases, the bleeder should be opened so as not to force the old fluid back into the master cylinder. Discard the fluid drained from the caliper as the piston(s) are pushed back in their bores…
Some front drive cars have also used the front calipers to operate the park brake. SAAB and Subaru are a couple and they require the tool to screw the pistons in as they’re rotated.
Generally, if the piston has a slot or a couple of notches on 2 or 4 sides, then it must be rotated as it’s squeezed.