A covering is easily mounted and/or demounted to envelop an overall sliding device with onboard moving-magnet linear motor. The covering helps improved propulsion, high velocity and response of a table even with small in dimension, compact in construction. End blocks are installed in opposite ends of a bed and a linear motor is placed between the bed and the table. The end blocks are made in solid bodies which are tightened to the bed together with a coil board. The end blocks have butting surfaces which can come into abutment against the ends of the table to protect the table from getting out of the bed. The end blocks have locking recesses which mate with locking jaws on the covering to fasten the covering to the end blocks.