to the arm 121 and a lower end of each piston is pivotably connected to a lug 142 on a skid 117 to which is secured a doghouse 140 initially the doghouse 140 is supported on a trailer l of a truck r fig8 e 8h illustrate the connection of the skid 117 to the suspending arms the apparatuses 123 a 123 b raise the skid 117 and whatever is on the skid 117 e g a doghouse 140 so that the holes ha of the arm are aligned with holes hb of the lugs 142 locking pins ps are then inserted through the holes to secure the skid 117 to the arm an hydraulically powered cylinder apparatus 123 k has a housing 123 m pivotably connected to the arm 121 and an end of an extendable piston 123 p pivotably connected with pins 123 l to a lug 143 on the skid 117 hydraulic power fluid is supplied to the three cylinder apparatuses from an hydraulic power unit hpu controlled by a control system cs shown schematically fig9 a 13c illustrate steps in a method according to the present invention for installing the doghouse 140 on the rig 100 as shown in fig9 a 9c the arms 121 122 are turned out 180 u00b0 as compared to their position in fig8 c the cylinders 123 k connected to the arms 121 122 used for removing the doghouse are pinned in place when rotating the arms the truck r is driven so the doghouse 140 is.