Candy Controls
When Timing is Everything

Foot-Mount Screw Jack

Quick Facts

  • Translating, Keyed, and Rotating worm gear screw jacks
  • Load capacity from 1,000 lbs. to 100 tons
  • Heavy load taper roller bearing design
  • Self-locking acme screw with max stroke of 6,000 mm
  • Single or multiple jack systems
  • Custom design available

Product Overview

Candy’s Foot-Mount Screw Jacks, FMJ Series, offer a low-cost solution to a wide variety of industrial lifting, lowering, pushing and pulling applications. Available in twelve sizes, these worm gear screw jacks feature a self-locking acme screw and can be ordered with a number of options and configurations, the most basic including Translating, Keyed or Rotating designs.

Technical Data

RATE OF TRAVEL

Travel is determined by the ratio of the worm gear screw jack, the standard ratio, N, produces 1mm of travel per one revolution of the input shaft, or worm. An input speed of 1,500 rpm equals 1,500mm of travel per minute. Maximum input shaft speed is 1,800 RPM.

The alternative ratio, L, produces 0.25mm of travel for each revolution of the input shaft. Based on an input shaft speed of 1,500 rpm, this ratio produces a linear speed of 375mm per minute.

Tolerances and Backlash

  • Trapezoidal screw end play is 0.15mm
  • Radial play is 0.2mm
  • Lifting screw outer diameter and sleeve diameter free tolerance is 0.2mm
  • Worm shaft and gear play is ± 3 degrees for ratio N, and ± 5 degrees for ratio L

LATERAL FORCE

Lateral force will reduce the working life of the screw jack and can lead to product failure. The screw jack(s) should be isolated from lateral forces via the use of guide rails. A Rotating or Traveling Nut-Type worm gear screw jack must be used in single jack applications with no external guiding.

SELF-LOCKING FUNCTION

Trapezoidal type screws are typically self locking. This function, however, depends on a variety of parameters, including, but not limited to screw pitch, screw jack ratio, lubrication, vibration, mounting position, etc. A brake or brake-motor may be required to guarantee holding position, please consult Candy Controls during the design process. A brake is recommended for all applications involving vibration.

STOP COLLAR

Following a customer’s requirement, screw jacks may be fitted with a stop collar to prevent the screw from being removed from the gearbox. A stop collar is not to be used as a fixed stop.

WORKING TEMPERATURES

Normal operating conditions are -20ºC to 80ºC. Please consult Candy Controls for applications that require temperatures outside this range.

LUBRICATION

Worm gear screw jacks are shipped from the factory with our standard NLGI Grade 2 grease. Recommended lubrication maintenance is recommended after the first 300 hours of use, and then every 1,000 hours of use thereafter.

FAQ

Q: What is the difference between a trapezoidal worm gear screw jack and a ball screw jack?

A: The trapezoidal screw jack uses a threaded acme screw that is typically self-locking, meaning it will hold its position without a brake. Ball screw jacks incorporate ball screws to convert rotary motion to linear movement. Ball screw jacks are inherently more efficient, requiring 1/3 the horsepower compared to trapezoidal worm gear jacks. Due to the efficiency of a ball screw jack, a brake must be used to stop and hold a load in position.

Q: What is a Translating or Keyed-Type Screw Jack?

A: This type of jack has a key fixed to the jack housing and inserted into a keyway milled into the lifting screw which forces the screw to translate through the gearbox housing without rotating.

Q: What is a Rotating or Traveling Nut-Type Screw Jack?

A: This design incorporates a lifting screw keyed to the worm gear as a single unit, forcing the lifting screw to rotate in the gearbox, but not translate. A traveling nut, running onthe rotating screw generates linear motion for the attached load. This type of jack is ideal for applications that cannot accommodate a screw protection tube.

Q: Which type of screw jack is best for a single jack system?

A: In a single jack application, with no guide rails to isolate lateral load, a Rotating or Keyed screw jack must be used. Multiple jack applications, or single jack applications that are fully guided may use Translating or Keyed-Type screw jacks.

Q: Can a screw jack be operated in multiple unit systems:

A: Yes, screw jacks may be easily configured in systems, motorized and manual, to raise and lower a load in unison.

Q: Can a worm gear screw jack be operated at high speed?

A: Input power should not exceed the KW rating in specification tables. Maximum gearbox speed should not exceed 1,800 rpm.

Specifications Overview

Model
Number
Max Static
Load
(ton)
Max Dynamic
Load
(ton)
Screw
Diameter
(mm)
Screw Pitch
(mm)
Available
Ratios
Max
Stroke
(mm)
FMJ-0.5T 0.5 0.3 20 5 5:1 10:1 20:1 500
FMJ-1T 1 0.6 24 5 5:1 10:1 20:1 750
FMJ-2T 2 1.35 25 5 5:1 10:1 20:1 750
FMJ-3T 3 2 32 6 6:1 12:1 24:1 1400
FMJ-5T 5 2.85 38 6 6:1 12:1 24:1 1700
FMJ-10T 10 6.4 45 8 8:1 16:1 32:1 2500
FMJ-15T 15 6.4 50 8 8:1 16:1 32:1 2800
FMJ-20T 20 8.4 64 10 8:1 16:1 32:1 3000
FMJ-30T 30 9.6 75 12 12:1 18:1 36:1 5000
FMJ-40T 40 10.3 80 12 12:1 18:1 36:1 6000
FMJ-50T 50 11 90 14 7:1 14:1 28:1 6000
FMJ-100T 100 26 100 16 8:1 16:1 32:1 6000

Screw Jack Top End Options

ordering

Ordering

fmj

Installation

Translating-type: lifting screw
rotation and do linear motion
Keyed-type: lifting screw anti-rotation
and do linear motion
Rotating-type: lifting screw fixed
rotation travel nut linear motion
csj-01 csj-02 csj-03

Input Forms

(single input) SB (double input)
SAR SAL
sar-01 sal sb
C (directive drive-single input) D (directive drive double input)
MCR MCL MDR MDL
mcr mcl mdr mdl

Multiple Jack Systems