Hand Operated Screw Jack Descriptions Hand operated screw jack is ideal solutions for applications where electricity or power generators is inconvenient or dangerous, light weight, low duty cycle, low target cost and short travel length.
Hand operated screw jack is composed of hand wheel or hand crank and a worm gear screw jack, which has intermittent precisely positioning and self-locking feature for no creeping down without brake mechanism or other locking systems, when manual ball screw jack, no self-locking feature, avoid ball screw back drive with attached load, which needs additional brake mechanism or other locking system to prevent it creep. Standard hand wheel dimensions from 5" to 20" diameter, larger diameter required, consulting JACTON sales.
Hand operated screw jack has a disadvantage, slow travel speed, maximum 1 to 1.5 mm travel length per full turn of hand wheel or hand crank. But hand operated bevel gear screw jack is ideal solution of slow travel speed with internal pairs spiral bevel gears drive, maximum up to 12mm travel length per full turn of hand wheel or hand crank. When you required manual screw jack, but need quick lifting speed, bevel gear screw jack will be the best choice.
When hand operated screw jack need precise position display, a range of digital position indicators are available. These digital position indicators measure the rotations of the input shaft and display corresponding position in the digital counter window. The display value per input shaft revolution is variable and is achieved through a series of gear reductions configured to accommodate different worm gear screw jack ratios, screw pitch and travel length.
Hand Operated Screw Jack Calculation Formulas Hand Manual Force Calculation Formulas F=(GxP) / (ixR) F: hand manual force (kg) G: load capacity (kg) P: lifting screw pitch (mm) i: worm gear reduction ratio R: hand wheel or hand crank radius (mm)
Travel Stroke Calculation Formulas 1. L=n x P/i L: travel stroke (mm) n: numbers of hand wheel or hand crank full turns P: lifting screw pitch (mm) i: worm gear reduction ratio 2. L1= P/i L1: travel stroke per turn of input shaft P: lifting screw pitch (mm) i: worm gear reduction ratio
Hand Wheels or Hand Crank Dimensions Cast Iron Hand Wheel Picture and Drawing