CYL,SLAVE,Specifications Item Description The Slave Cylinder may also be refered to as the Platform Level Cylinder. This cylinder is typical affixed to the end of the fly boom closest to the platform. The Slave Cylinder works in conjunction with the Master Cylinder (typically at the rear of the boom), to keep the operator's platform level as it travels up and down. It is used on various Mobile Elevated Work Platforms (MEWPs). Always refer to the machine serial