Helicopters with landing skids, no wheels; How are they taken in and out of a hangar? I'm sure many helicopters also need/use Hangars frequently. How do you take them to a hangar and take them out of it without wheels?

Specially when they have to be taken indoors for some maintenance work on them. Are there any special forklifts/carts used for ground handling of helicopters that do not use wheels and need to be moved without actually flying?
Basically, you put wheels on the skid and tow them. 

In some cases, towing wheels are attached to the skids (which usually have sleeves in them for mounting), and a tow bar is attached to the front (one or two sets of wheels may be attached to the skids), which is then towed by a vehicle.



Image from incrediblediary.com

There are also specialised tow carts available for helicopters, which basically grip the skids (usually in a couple of places on either side) and lift them up, after which the helicopter can be moved by the operator by controlling the cart.



Image from hasmak.com