An orbital disk grinder comprises a housing, grinding disk which can be applied to a working surface, a motor for moving the grinding disk so that the grinding disk gyrates in a circular orbit and simultaneously rotates about its axis, and speed control means operative for setting a speed of the grinding disk low when a normal force acting on the working surface is low, and high when the normal force acting on the working surface is high, so that a normal force acting on the grinding disk serves as a setting variable of the speed control means.

An eccentric disk grinder has a grinding disk, an eccentric shaft fixedly connected with the grinding disk, a motor, a shaft having an axis arranged so that the motor eccentrically, circulatingly and rotatably moves around the axis of the shaft, with the eccentric shaft being rotatable relative to the shaft, a braking device provided for delaying movement of the grinding disk and having a braking element which follows the movement of the grinding disk and is delayable relative to the grinding disk.

A sander (1) has a motor (3) with a motor shaft (4) mounted in a bearing box (11) via an eccentric ball bearing (10). Coupled to the bearing box (11) is a pad (12) having a bulged square shape in a horizontal cross section. The sander (1) further includes a skirt (6) with an opening (6a) on which a synthetic (polyurethane rubber) brake ring (17) is mounted. The brake ring (17) comprises an outer peripheral portion (18) and a plurality of contact portions (19) disposed at regular intervals around the outer peripheral portion (18). Each contact portion (19) is bulged toward the center of the brake ring (17) with both ends connected to the outer peripheral portion (18). Also, the contact portions (19) are elastic so as to deform in the radial direction. The contact portions (19) together form a through-hole (21) which is slightly smaller than the bearing box (11) for receiving the bearing box.

The invention is based on a hand power tool that comprises a motor (12)--with a motor shaft 14--located in a housing (10), which said motor shaft is supported via a shaft bearing (18) located on a side closest to a backing pad (16) and that is interconnected in torsion-resistant fashion with an eccentric sleeve (22) in a seat (20). It is proposed that the eccentric sleeve (22) projects in the axial direction (56) at least partially into the shaft bearing (18), and at least part of the axial space of the shaft bearing (18) is used to form a drive connection with the eccentric sleeve (22).

A polishing machine includes a body. A driving motor is installed in the body. The driving motor has an eccentric shaft mounted at a bottom of the motor, and a polishing wheel connector mounted under the eccentric shaft. A dust shield is mounted on the body and outside the driving motor. Multiple brake units are mounted at a bottom of the dust shield. A polishing wheel is mounted under the dust shield and fastened on the polishing wheel connector by a threaded pin formed at a center of the polishing wheel. The polishing wheel is in contact with the multiple brake units.