28. MACHINES READY FOR ATTACHMENTS 28.1 EXPLANATION OF COMPONENTS 1. STOP VALVE This valve stops the flow of the hydraulic oil. a FREE : Hydraulic oil flows. b LOCK : Hydraulic oil stops. Set this valve to the LOCK position when removing or installing at- tachments. 2. SELECTOR VALVE This switches the flow of the hydraulic oil. For details of the attachment to install and the direction of right 3-way valve a , see 28.2 ‘HYDRAULIC CIRCUIT”. PC450-ENG 5-5