In a method for adjusting the clamping force which is exerted by a parking brake and is generated by an electric brake motor, in the event of a jump in the voltage or the current of the electric brake motor, a correction current is ascertained on which the calculation of the motor parameters is based. The platform includes a deck constructed to be of an overall density less than that of water and sized so as to support the load above the level of the water. In one example, each gripper includes a sleeve within which the prongs are moveable so that the prongs are manipulated between the neutral, closed and released positions. The electronic book coupon deductor 25 deducts an electronic worth equivalent to a price according to page data requested to be readout, from the electronic book coupon.