The Winch Drives Gear Boxes are planetary gear units, with rotating outer casing, designed to be fitted into the winch drum: the PWD series for drive applications varies from 3 to 12 tons and the SLW-SCW series for applications exceeding 12 tons. These winch drives have two flanges close together: one is bolted to the fixed winch frame and the other is bolted to the drum, thereby serving as its first support. The drum and winch frame come in any shape and size: the only engineering restriction is the spigot on the flange coupling when fitted. The winch drives are attached to the drum with bolts inserted from the motor side to permit easy, immediate access to filling, level and drain plugs. PWD and SLW-SCW series performance has been rated in conformity with FEM M5 standards, with an output speed of 15 rpm, which are the most widely accepted standards on the market for self-propelled and on-board cranes.