Abstract: A sheet folding device includes a platform and a pair of guides disposed along opposite sides of the platform. The platform has a multi-stepped profile in a lengthwise direction so as to define a lower shoulder and an upper shoulder disposed above and displaced in the lengthwise direction of the platform from the lower shoulder. The guides are provided for guiding placement of a sheet on the platform such that the sheet can be folded by (i) placing one edge of the sheet against one of the lower and upper shoulders, (ii) curling an opposite edge of the sheet and placing the opposite edge against the other of the lower and upper shoulders, and (iii) pressing the sheet downward onto itself on the platform so as to fold the sheet.

Abstract: A differential lift hoist apparatus includes an endless roller-and-link chain and upper and lower rotatably mounted spaced sprockets. The chain includes a pair of vertically-extending side-by-side loop sections. Each loop section has outer and inner leg portions and a lower bight portion interconnecting them. The chain also includes an upper bight section which interconnects the outer leg portions and a lower bight section which interconnects the inner leg portions. A group of the upper sprockets entrain and support the upper bight section, whereas a single upper sprocket spaced below the group of upper sprockets entrains and supports the lower bight section. The lower sprockets entrain and are supported by the respective lower bight portions of the chain loop sections.