Verification The Stability Of Screw
Calculation Formulas: Pcr=fm*d⁴/L²    ensure    Pcr>W*SF (SF=4) 
Pcr = Critical load (N)
d = Thread root diameter (mm)
fm = Support factor
L = Distance between load supporting point and mounting point as drawing (mm)
W = Equivalent load of single jack (N)
SF = Safety factor (generally SF=4)
Verify the screw stability when the axial compression load exists. If the load is greater than the critical load, increase the sizes before calculation.
A = 1*10⁵, B = 2.5*10⁴, C = 2*10⁵


Calculation Of Worm Gear Ratio
Calculation Of Required Power
Calculation Of Required Torque
* Input Torque: T=(F*p / 2*π*i*η) + To
* Input Power: P=F*V / 60*η, P=T*n/9550, V=n*p / 1000*i
* Worm Gear Ratio: I=(n / 1000*V)*p
* Stroke: S=n*p / i
* Travel Per Turn Of Input Shaft: L=p/i
* Hand Turnning Force: HF=T/R, HF=F*p / i*R*1000
T = Input torque (Nm)
F = Given load (N)
p = Screw pitch (m)
i = Gear ratio (ex. 24:1, i = 24)
η = Jack efficiency 
To = Idling torque (Nm)
P = Input power (kW)
V = Screw axial speed (m/min)
n = Jack input speed (rpm)
S = Stroke (mm)
L = Travels (mm) per turn of jack input shaft
HF = Hand turning force (kg)
R = Radius of hand wheels (m)

Calculation Of Equivalent Load Of Single Jack W(N)
Calculation Formulas: W=Ws / (Arrangement Factor*Number Of Jacks In Arrangement)
Ws: Total Equivalent Load Ws (N)

Number Of Jacks In Arrangement	1	2	3	4	5~8
Arrangement Factor	1	0.95	0.90	0.85	0.80

Calculation Of Duty Cycle
Calculation Formulas:  Duty Circle %ED: ED=work time in one load circle / (work time in one load circle+rest time in one load circle).
Acme screw: the unit of %ED for single screw jack is 1 minute duty circle max. 40%ED; 10 minutes duty circle max. 30%ED; 60 minutes duty circle max. 20%ED.
Ball screw: the unit of %ED for single screw jack is 10 minutes duty circle max. 50%ED; 30 minutes duty circle max. 30%ED; 60 minutes duty circle max. 20%ED.