anti-backlash reverse worm gear lifting jacks, zero backlash machine screw actuators, low backlash...

Jacton Electromechanical Co.,Ltd | Tel: +86 (0)769 81585852 | Fax: +86 (0)769 81620195 Email: [email protected] | Web: www.screw-jack.com | Skype: jactonjack

Anti-Backlash Screw Jacks Screw jacks are used for positioning loads in numerous applications, however when the

load direction alternates between tension and compression within the operating cycle and

a high position accuracy must be maintained then a specific type of screw jack is

required. The Anti Backlash Machine Screw Jacks is recommended for such applications,

as it is able to reduce the axial backlash between the lead screw and the trapezoidal

screw thread in the gear to a practical minimum.

Axial backlash exists in standard screw jacks as the "gap" or "play" between the flanks of

the lead screw thread and the internal thread on the worm gear nut. This gap or play is

due not only to normal manufacturing tolerances, but to the fact that there must be some

clearances to prevent binding and galling when the screw jack is operating under load. In

most applications either the load direction is constant so axial backlash does not occur or


the position error caused by the axial backlash is considered negligible for the application.

However some applications require minimal or regulated axial backlash for accurate and

repeatable positioning. Such an application is for positioning the rollers in steel

straightening machines for tube, bar or sheet steel production.

Anti-backlash mechanism on screw jacks can be used to reduce axial-backlash to a

practical minimum or a regulated value. Reduction in axial backlash below this minimum is

not normally recommended as it can cause binding and excessive wear. As the screw jack

is operated over time the axial backlash will increase as the lead screw thread on the gear

wears due to normal operation. To compensate for this anti-backlash device can be

adjusted to re-set for the required amount of regulated backlash. To help with the

identification of wear machine screw jacks can also be fitted with a wear monitoring device

for visual use or with electronic sensing for integration into a motion control system.

Anti Backlash Screw Jacks Application Case 1

Above picture is special manufactured 450MM Stroke Inverted 2 Ton Anti Backlash Screw

Jack following customers requirements. The assemblies can be adjusted in the future, to

maintain the zero backlash, and precise location. Two flanges Anti Backlash Screw Jack,

big flange for IEC90 motor, another small flange for geared potentiometer. Special devices

like anti-backlash device, anti rotation keyed screw configurations, travel stroke controlled

limit switches, lengthening threads end, anti rust and anti dust protection tube etc.


Anti Backlash Screw Jacks Application Case 2

10" Stroke Inverted 2 Ton Anti-Backlash Gearing Screw Jack application in precision

Single-Point Adjustment (SPA) in roll forming tube and pipe, tube mill, pipe mills

industries. The assemblies can be adjusted in the future, to maintain the zero backlash,

and precise location. Non-Standard Lengthening Worm Shaft Anti-Backlash Gearing

Screw Jack, mechanical digital position indicator / counter is mounted on Non-Standard

Lengthening Worm Shaft. Manual operation two jacks system. Special devices like

anti-backlash device, lengthening worm shaft, anti rust and anti dust protection tube, cast

iron hand wheel etc.

Anti Backlash Screw Jacks FAQs

What are anti-backlash devices?

Anti-backlash devices are internal jack components used to minimize backlash (free

movement between the lifting screw and nut) in machine screw jacks.

Why are anti-backlash devices needed?

Anti-backlash devices are typically used in reversing load applications where the lifting

screw position is critical.

Where are anti-backlash devices used?

Anti-backlash devices are frequently used in steel mill applications where the screw jacks

are used to set and maintain the position of the movable upper roll of a rolling mill. In

operation, the initial weight of the roll pulls the lifting screw to one side of the nut. When

steel passes through the rolls, the load reverses on the lifting screw and movement in the

opposite direction is limited by the anti-backlash device. Other common applications


include screw jacks used to position communication antennas and solar panels. In these

applications, directional changes in the wind can buffet the panels thus affecting the

position of the lifting screw. During these high wind conditions, anti-backlash devices

minimize the lifting screw movement.

Will the anti-backlash device require adjustment?

When the internal nut threads begin to wear, lifting screw backlash increases. Subsequent

adjustment of the anti-backlash device compensates for the nut wear and allows the user

to limit the backlash to the recommended value. Adjustment frequency will vary depending

on load, duty cycle, and temperature. The anti-backlash device should be replaced when

no further adjustment is possible due to thread wear.

What effect do anti-backlash devices have on torque requirements?

Torque requirements for screw jack operation are affected by the clearance between the

lifting screw and nut thread. Adjusting anti-backlash devices (within recommended values

for each design) will not increase the torque to move a given load. If the backlash is set

below the recommended values, torque values will increase significantly and thread wear

will accelerate.

Can anti-backlash devices be used on ball screw jac ks and bevel ball actuators?

No. Rather, the use of oversized ball bearings in ball nut assemblies is recommended to

reduce endplay in ball screw jacks and bevel ball actuators.

“JACTON” Company Profiles

Precision worm gear screw jacks, lifting jacks, machine screw actuators, ball screw jacks,

trapezoidal screw jacks, bevel gear screw jacks, worm gear driven lift mechanism, spiral

bevel gears right angle gearbox, miter gears drives 90 degree gearbox, multiple units

screw jack lifting system arrangements manufacturers and suppliers in China – Jacton Electromechanical Co.,Ltd . Since 1997, only occupied 500 square meters for factory, up

to 2012, factory is occupied 5000 square meters with 55 employee staffs. With senior

engineers, experienced skilled workers and practiced sales teams, our company

consistently provides ideal mechanical power transmission solutions.

Application in roll forming line, theater stage lift table, solar tracking system, earth station

antennas, hydropower sluice gate, food processing line, coil sheet slitter line, tension

leveling line and straightening line, continuous galvanizing line, beverage production line,

railway maintenance lifting jack, angle tilt adjustments with double clevis, aircraft docking

system, printing press, plastic extruder, sewage auger, bonding equipment, metering

auger, sewage agitator, newspaper conveyor, bottling equipment, material handling, web

finishing, paper conveying, conveyor, cardboard box equipment, packaging, vertical pump

drive, sand spreader, residential mower, snow blower, mining equipment, crane,

agricultural, grain wagon, harvester, forage harvester, manure spreader, fertilizer spreader

and sewage conveyor etc.


Manufacturing Equipments include cnc lathes, gear cutting hobbing machines, radial

drilling machines, high speed thread whirling machines, worm shaft grinding machines,

vertical milling machines, high precision CNC machine tools, cnc precision automatic

lathes, lathes, punching machines, hydraulic straightening machines, polisher machines.

Testing equimments include noise meters, infrared thermometers, hardness testers, gear

meshing testing machines, micrometers, testing lifting screw moving smoothly adjustable

working table.

Customers are distributed throughout the world, such as USA, Canada, Mexico, Brazil,

Argentina, Chile, Australia, New Zealand, Japan, Korea, Thailand, India, Indonesia,

Malaysia, Philippines, Singapore, Vietnam, Sri Lanka, Pakistan, Iran, UAE, Saudi Arabia,

Turkey, South Africa, Egypt, Zambia, Germany, UK, Poland, Sweden, Slovak, Spain,

Greece, Italy, Russia, Netherland, Danmark, Belgium and Other Countries.

anti-backlash reverse worm gear lifting jacks, zero backlash machine screw actuators, low backlash...

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