Skating force
The skating force is so called because it causes the tonearm to glide over the record from the outside to the inside, so to say 'to skate'. This force which draws the tonearm to the center of the disc ensues indirectly from the friction between the tracking diamond and the record. This friction force always takes effect in the direction of the tangent line. If the pivot point of the tonearm is not located on the tangent, the friction force is divided into two components: one takes effect in the direction of the pivot point of the tonearm, the other takes effect towards the centre of the disc. |
The force Ft results from the friction between the record and the tracking diamond. It acts tangentially. Because the pivot point is not located on the tangent, this force is divided into Fa which acts in the direction of the pivot point and Fs which is the skating force. |
The valule of the skating force is not easily determined. It depends on the tracking weight, the circumferencial speed, the record itself as well as on the tonearm and diamond geometry.
Although the Thales' Tonearm is a tangential tonearm, there is also a skating force because the aligning part of the tonearm is of variable length and would therefore be protracted through the frictional force between the record and the tracking diamond. The skating force which decreases sinusodially towards the centre of the record is continuously compensated.