any of the sprockets shown but preferably one which has a fixed position relative to the track e g sprockets 201 202 203 204 207 and 209 and to a lesser extent sprockets 205 208 and 210 because these sprockets desirably have the facility of being readily adjusted in order to synchronise the disengagement and re engagement of the pins 109 with the block head 108 and to achieve effective chain tension the sprockets shown may be driven directly by motor and gear reduction unit and or via a motor drive chain and sprocket arrangement to a common shaft alternatively a drive station 211 including drive sprockets may be positioned between sprockets 204 205 and 206 where pin to block contact is not being made in order to facilitate the smooth transition of a slide block from one track length to another around a corner the corners may be mitred as shown at 116 in fig4 the various track sections can readily be adjusted by vertical adjustment from their support brackets not shown and the fact that the conveyor track 101 is made in two open top sections allows these sections to be released from the support brackets in pairs of independently without disturbing the sprockets pins or conveyor chain a garment support unit.