Synchronized multi-jack systems keep platforms level without four independent servo axes. One motor turns every worm gear screw jack input at the same rate through a rigid train of miter bevel gearboxes and line shafts. Anand Gears catalogues jacks from 5 kN to 350 kN and matches bevel sizes into multi-point systems (2-, 3-, and 4-point are standard patterns). A representative four-jack platform is described in the synchronized screw jack platform case study.
Why mechanical sync works
Each jack’s worm input is geared to the same shaft train. If one corner is harder to lift, torque redistributes; travel still matches because the screws cannot advance independently. That is the opposite of four free motors racing against friction differences.
Building blocks
- Worm gear screw jacks — TP or TPR, Tr or ball, sized per corner (kN).
- Miter bevel gearboxes — 90° power turn; often 1:1 miter for equal speed (bevel ratios up to 1:12 appear on multi-jack matching hardware when reduction is needed). Product page: bevel gearboxes.
- Line shafts — solid shafts between nodes; length from jack centre distances (mm).
- Couplings — flexible jaw types tolerate small misalignment; rigid types when alignment is guaranteed.
- Motor + optional gearmotor — IEC B5/B14 flanges (frame sizes 56–180 on jack product accessories) and limit switches at stroke ends.
2-jack layouts
I-layout (in-line): motor — shaft — jack A — shaft (or through shaft) — jack B. Simplest for a long narrow table with two lift points.
L-layout: motor on one leg; a single miter bevel turns 90° to the second jack. Common when the motor must sit off the platform edge.
Torque path: motor torque splits or passes through; each jack sees its share of load torque reflected through the worm ratio. Size shafts for the higher continuous torque segment (usually nearest the motor if both jacks load equally, or the path to the heavier corner).
4-jack layouts — H, U, I
H-layout
A central crossbar (primary shaft) with two side branches. Motor often sits on the primary. Four miter nodes (or combinations of T/cross miters) feed four corner jacks. Good for rectangular platforms with clear centre access. This is the pattern used in the four-jack case study.
U-layout
Shafts along three sides of the rectangle; one side open for maintenance or conveyor access. Miters at three corners (or four with a blind end). Useful when one edge must stay clear of hardware.
I-layout (spine)
One central longitudinal shaft with bevel take-offs left and right to each jack. Compact when the machine has a centre tunnel or beam. Watch intermediate bearing supports on long spines.
Product material also references 2-point (L-type bevel), 3-point (T-type), and 4-point (cross bevel) families — names describe the node geometry more than the letter of the plan view.
Torque path checklist
- Start from each jack: load (kN) → screw pitch → worm ratio → input torque at the jack shaft.
- Add path losses (bevel efficiency, coupling) with engineering judgment — do not ignore multi-node stacks.
- Sum torques on each shaft segment; the motor must cover the total plus start-up.
- Confirm jack thermal duty (intermittent) still holds when all corners move together.
Coupling selection (practical)
- Flexible jaw / elastomer — default for industrial pedestals with small parallel/angular error.
- Rigid — short spans, carefully aligned housings, maximum stiffness.
- Guards — rotating line shafts need covers; design access for greasing miters.
Drive sizing for the system
Motor power is not “one jack × four” if duty is intermittent and only friction differs — but you must still cover simultaneous lift of all corners under worst-case load share. Use the jack catalogue speed/torque data for the chosen ratio class (1/4 through 1/32 depending on size), then size the motor and any primary reducer. Limit switches protect over-travel; they are not a substitute for correct duty sizing.
When electronic multi-drive is better
If the machine must reconfigure spacing, lift only two of four points, or follow complex trajectories, independent motors may win. For fixed-geometry even lift and hold, the mechanical H/U/I train remains the simple industrial default.
Related: Screw Jack Lifting Systems · Bevel Gearboxes · How to Size a Screw Jack · Contact