JT Series Acme Screw Jack 1
Contents General Information -------------------------------------------------------------------------- 3 Configurations---------------------------------------------------------------------------------- 4 Permissible Buckling Load----------------------------------------------------------------- 5-6 Specifications 1. JT-0.5T, JT-1T, JT-2T ---------------------------------------------------------------------------- 7 2. JT-3T, JT-5T, JT-10T ----------------------------------------------------------------------------- 8 3. JT-15T, JT-20T, JT-30T -------------------------------------------------------------------------- 9 4. JT-40T, JT-50T, JT-100T------------------------------------------------------------------------- 10 Selection Guides 1. Jack Series---------------------------------------------------------------------------------------- 11 2. Load Capacity ------------------------------------------------------------------------------------ 11 3. Screw Configurations & Mounting Orientation ------------------------------------------------- 11 4. Travel Stroke-------------------------------------------------------------------------------------- 11 5. Gear Ratio ---------------------------------------------------------------------------------------- 12 6. Screw End Fittings-------------------------------------------------------------------------------- 12 7. Worm Shaft Input Type--------------------------------------------------------------------------- 12 8. Accessories --------------------------------------------------------------------------------------- 13 Selection Example ----------------------------------------------------------------------------- 14 Dimensions 1. Model JT-0.5T ------------------------------------------------------------------------------------ 15 2. Model JT-1T -------------------------------------------------------------------------------------- 16 3. Model JT-2T -------------------------------------------------------------------------------------- 17 4. Model JT-3T -------------------------------------------------------------------------------------- 18 5. Model JT-5T -------------------------------------------------------------------------------------- 19 6. Model JT-10T ------------------------------------------------------------------------------------- 20 7. Model JT-15T ------------------------------------------------------------------------------------- 21 8. Model JT-20T ------------------------------------------------------------------------------------- 22 9. Model JT-30T ------------------------------------------------------------------------------------- 23 10. Model JT-40T ------------------------------------------------------------------------------------ 24 11. Model JT-50T------------------------------------------------------------------------------------- 25 12. Model JT-100T ----------------------------------------------------------------------------------- 26 Application Examples ------------------------------------------------------------------------- 27 Operation Manual ------------------------------------------------------------------------------- 28-32 Frequently Asked Questions ---------------------------------------------------------------- 33-36 Company History -------------------------------------------------------------------------------- 37 Contact Us ----------------------------------------------------------------------------------------- 38 2
General Information Features * Model JT-0.5T, JT-1T, JT-2T, JT-3T, JT-5T, JT-10T, JT-15T, JT-20T, JT-30T, JT-40T, JT-50T, JT-100T * Static load capacity from 0.5ton to 100ton, dynamic load capacity from several kilograms to 26ton * Self locking acme screw, precise positioning, uniform lifting speed * Translating screw, anti-rotation keyed screw and rotating screw configurations * Upright mounting, inverted mounting, double clevis pivot mounting * Top plate, threaded end, clevis end and plain end fittings * Manually operated, electrically driven or both * Individual or multiple screw jack lift system arrangements * Each jack has three worm gear ratios, high speed, medium speed, low speed * No standard travel length, all screw jack stroke produced following your needs 3
Configurations Self Locking Acme Screw 1. Acme screw rotary cutting processing machine, high precision 2. 40Cr or C45 steel material, customized stainless steel screw 3. Minimum friction for smooth operation and longer life 4. Self-locking, load holding without brake mechanism and locking system, accurate positioning 5. Minimum axial backlash Tapered Roller Bearing 1. Preloaded for reduced assembly spring rate and high thrust load 2. Provides excellent support for side loading and horizontal applications 3. Maintains exact gear alignment under separating and thrust forces 4. Bearing sized for endurance and maximum loading conditions Bronze Worm Gear 1. Precison hobbing machine for processing 2. Bronze material, high hardness, excellent wear resistance 3. Worm gear center design for long life Worm Shaft 1. Worm rotary cutting processing machine and grinding machine processing, high precision 2. High frequency heat treatment of worm, 40Cr or C45 steel material, high hardness, customized stainless steel worm shaft Rugged Housing 1. CNC precision automatic lathe processing 2. Cast iron or ductile cast iron material, customized alloy steel material Grease Seals 1. Double lip grease seal, prevent grease leak 4
Permissible Buckling Load n = 1/4 Concerning the variety of models and loading methods at screw end, as well as screw length and permissible buckling load, please refer to the following charts or formula Pcr = nπ 2 E(K/L) 2 A a n: shaft end support factor (1/4, 1, 2) E: lengthwise elastic modulis 2.1x10 4 kgf/ 2 K: minimum auxiliary radius k = d1 / 4 d1: thread root diameter 15 ~ 84 L: shaft support length, as demand A: thread root sectional area A = π(d1) 2 / 4 a: safety factor a = 0.25 thread root diameter datas 0.5T(15) 1T(19) 2T(20) 3T(26) 5T(32) 10T(37) 15T(42) 20T(54) 30T(63) 40T(68) 50T(76) 100T(84) 5
n = 1 n = 2 Example: Pcr: 1000kg (load) L: 1000 (length) Jack fixed shaft terminal free n=1/4 Pcr = nπ 2 E(K/L) 2 A a Pcr = 1/4 x 3.14 2 x 21000kgf/ 2 x ( d1 / 4L) 2 x 3.14x (d1) 2 / 4 x 0.25 Pcr = 1/4 x 3.14 3 x 21000kgf/ 2 x d1 4 / 16 2 L 2 1000kg = (3.14 3 x 21000kgf/ 2 x d1 4 ) / 16 2 x 1000 2 2 x 4 d1 4 = (16 2 x 1000 2 2 x 4 x 1000kg) / (3.14 3 x 21000kgf/ 2 ) d1 4 = 1575040.5 4 d1 = 35.426 thread root diameter d1 = 35.426 Following thread root diameter datas JT-10T(37) is suitable, so select JT-10T model jack. 6
Specifications JT-0.5T Specifications JT-1T Specifications JT-2T Specifications 7
JT-3T Specifications JT-5T Specifications JT-10T Specifications 8
JT-15T Specifications JT-20T Specifications JT-30T Specifications 9
JT-40T Specifications JT-50T Specifications JT-100T Specifications 10
Selection Guides JT - 5T - UR - 300 - H - II - C - HW 1 2 3 4 5 6 7 8 1. Jack Brand JT: Jacton brand screw jack 2. Load Capacity Model 0.5T 1T 2T 3T 5T 10T Load capacity 0.5 ton 1 ton 2 ton 3 ton 5 ton 10 ton Model 15T 20T 30T 40T 50T 100T Load capacity 15 ton 20 ton 30 ton 40 ton 50 ton 100 ton 3. Screw Configuration & Mounting Orientation US: Upright translating screw UK: Upright keyed screw UR: Upright rotating screw IS: Inverted translating screw IK: Inverted keyed screw IR: Inverted rotating screw 4. Travel Stroke 300, means travel stroke 300 No standard travel stroke, all screw jack stroke produced following your needs 11
5. Gear Ratio Each jack model has three gear ratios H: high gear ratio M: medium gear ratio L: low gear ratio Model 0.5T 1T 2T 3T 5T 10T 15T 20T 30T 40T 50T 100T H 1/5 1/5 1/5 1/6 1/6 1/8 1/8 1/10 1/12 1/12 1/7 1/8 Travel Per Turn 1 1 1 1 1 1 1 1 1 1 2 2 Worm M 1/10 1/10 1/10 1/12 1/12 1/16 1/16 1/20 1/18 1/18 1/14 1/16 Travel Per Turn 0.5 0.5 0.5 0.5 0.5 0.5 0.5 0.5 0.67 0.67 1 1 Worm L 1/20 1/20 1/20 1/24 1/24 1/32 1/32 1/40 1/36 1/36 1/28 1/32 Travel Per Turn Worm 0.25 0.25 0.25 0.25 0.25 0.25 0.25 0.25 0.33 0.33 0.5 0.5 6. Screw End Fittings Standard lift screw end fittings includes top plate, clevis end, threaded end, plain end. If you have your own lift screw end fitting design, we can make them following your requirements. 7. Worm Shaft Input Types A: left side worm shaft input. B: right side worm shaft input. C: double worm shaft input. M1: left side motor flange direct input. M2: right side motor flange direct input. M3: left side motor flange direct input, right side worm shaft input. M4: right side motor flange direct input, left side worm shaft input. 12
8. Accessories N: No accessory PP: Protective pipe (lifting screw dustproof and rustproof) BB: Bellows boot (lifting screw dustproof and rustproof) HW: Hand wheel (hand operated jack, optional hand crank) DC: Digital counter or digital position indicator (installed on worm shaft, precision display stroke) EM: Electric motor (motor driven jack, optional ac motor or dc motor) GR: Gear reducer (motor driven jack with low speed, optional gear motor, worm gear reducer, helical gear reducer) LS: Limit switches (control stroke, when full extend or full retract travel, the motor will stop ) SN: Stop nut (installed at the bottom of lifting screw, prevent lifting screw from being removed from the jack housing) PB: Pillow block bearing (when long distance between jack and jack, which fixes connecting shaft, avoid swing) FC: Flexible coupling (for shafts connection like connecting shaft and worm shaft) CS: Connecting shaft (for connecting drive shafts like screw jack lift system) BG: Miter gearbox (right angle transmit rotary motions, power or torque in screw jack lift system) SP: Swivel plate or trunnion mounting plates (installed on jack base with swivel pins for pivoting of loads) SM: Swivel mounting base or trunnion mounting base (matching swivel plate or trunnion mounting plates) 13
Driven Machine Factor (f1) Selection Examples Arrangement Factor Examples: 6Ton load, upright mounting, lifting speed 375/min, travel stroke 750, full guided, top plate end, four screw jacks synchronized lifting system. Screw Jack Selection 1. From driven machine factor f1 max = 1.3, Lifting system total load = 6 x 1.3 = 7.8Ton, Each jack load = 7.8 / 4 = 1.95Ton. Upright mounting, means compression load. Following the information of 1.95ton load each jack, 375/min (6.25/s), we can check 6 th page specifications, select JT-5T jack model, lifting screw diameter 38, pitch 6. 2. Following 375/min travel speed, worm gear raio i = (1500rpm x 6 pitch) / 375/min = 24 3. Following travel stroke 750, full guided, we check permissible buckling load (n=2) charts, 750 stroke is within the range of bending length. Screw jack model: JT-5T-US-750-L-I-C-N Bevel Gearbox Selection Power = (7800kg x 0.375m/min) / (6120 x 0.15) = 3.19Kw. From above arrangement factor, four screw jacks synchronized lifting system factor is 0.85. So system required power = 3.19 / 0.85 = 3.75Kw. Input torque = 9550 x 3.75Kw / 1500Rpm = 23.875Nm. Check bevel gearbox JT series catalogue with 1:1 ratio, select JT-19 gearbox is enough. Calculation Formulas 1. Total equivalent load kg = load max x f1 2. Worm gear ratio = (input rpm / travel speed /min) x pitch 3. Required power = (total equivalent load kg x tavel speed m/min) / (6120 x η eff.) 4. Required torque = 9550 x power kw / input rpm 14
Dimensions Model JT-0.5T Dimensions 15
Model JT-1T Dimensions 16
Model JT-2T Dimensions 17
Model JT-3T Dimensions 18
Model JT-5T Dimensions 19
Model JT-10T Dimensions 20
Model JT-15T Dimensions 21
Model JT-20T Dimensions 22
Model JT-30T Dimensions 23
Model JT-40T Dimensions 24
Model JT-50T Dimensions 25
Model JT-100T Dimensions 26
Application Examples JT series screw jack is application in steel mills roller adjustment, pipe mills roller adjustment, tube mills roller adjustment, roll forming mills roller adjustment, plate mills roller adjustment, rolling mills rollers adjustment, powered feeder straightener rolls adjustment, roller system adjustment, adjusting synchronous coil feed lines rolls, precision roller leveler, cold roller adjustment, hot roller adjustment, coil handing, semi-finished product handling, brush adjustment belt cleaning, zinc pot lifting mechanism, air knife system adjustment, roll pass system, sizing stand, molten steel pot lifting system and anywhere required raising, lowering, pulling, pushing and rolling linear motions. For examples>>>>>> powered feeder straightener rolls adjustment Inverted type screw jacks are used for straightener rolls adjustment for superior alignment and reduced operator effort. All rolls are individually adjusted. Six jacks or eight jacks are used in a machine, regular jacks models: 1. JT-1T-IS-100-M-IV-C-PP 2. JT-2T-IS-100-M-IV-C-PP 3. JT-3T-IS-100-M-IV-C-PP 4. JT-5T-IS-120-M-IV-C-PP 5. JT-10T-IS-150-M-IV-C-PP Models Explanation: 1T, 2T, 3T, 5T, 10T: jacks models IS: inverted translating screw 100, 120, 150: unit, it s travel length M: medium worm gear ratio, 0.5 travel per full turn of worm IV: threaded end C: double worm shaft PP: protective pipe 27
Operation Manual Read this manual before installation or operation of screw jack. Failure to understand this manual, install or operate screw jack properly could result in damage to the Jack and or serious personal injury. Do not exceed the screw jack ratings including design load, travel, and input speed. Install, align and shield all moving parts properly. Proper machinery installation practices should be followed. Safety codes for mechanical power transmissions apparatus are to be followed. Check for and adhere to all applicable safety codes. Bolts should be sized to fit the screw jack base mounting holes, at least grade 5 and tightened to the appropriate torque. Mounting bases should be flat and sufficiently strong to support the load on the jack. Properly lubricate and maintain the screw jacks. Use the operation manual only for the intended application. Failure to install, operation or maintain screw jacks could result in product failure and personal injury. This screw jack operation manual is applicable to all screw jacks models. Information represents typical configuration and may different slightly from the actual screw jack being installed or repaired. Notices Before Installation Your screw jack was manufactured to high quality standards and is designed to provide long service life. Certain safety measures and procedures must be followed in handling, installing and servicing the screw jack to insure long trouble free service. 1. Any obvious or suspected damage to screw jack during transport from the factory must be iediately taken pictures and reported to Jacton corresponding sales and the carrier, The sales will submit this problem to Jacton engineers teams iediately. 2. Upon delivery all of the screw jack should be inventoried to determine if shortages exist. All shortages must be iediately taken pictures and reported to Jacton corresponding sales and the carrier, The sales will submit this problem to Jacton QC teams and warehousers iediately. 3. Installation, maintenance and safety instructions must be given to personnel directly responsible for the installation, maintenance and operation of the jack. Caution! Screw jacks are normally self-locking. Vibration could cause a screw jack to self-lower or creep. Stop nut is used to prevent lifting screw moving out of the screw jack base. Jacton standard screw jacks are not equipped with stop nuts unless special requirements in your purchase order. Screwjacks are not meant for personnel support. All applications designed for personnel support must be approved by Jacton engineers team. 28
Installation Instructions 1. Be certain that the screw jack load capacity exceeds the maximum load that may be applied to it. 2. Be assured the screw jack input speed is not be exceeded. Specifications show the max. speed. 3. The foundation for the screw jack should be rigid enough to maintain correct alignment with connected machinery and have sufficient strength to support the maximum load. 4. The foundation should have a flat mounting surface in order to assure uniform support for the screw jack. Be assured the opening in the foundation for the protective pipe or the lifting screw is as small as possible in order that the jack is supported over the greatest possible area. 5. Check the method of stopping the screw rotation, maybe translation will occur is sufficiently strong. When individual screw jack application without be guided, will need keyed screw jack. 6. It is extremely important that the screw jack be installed so that the lifting screw is perfectly plumb and all connecting shafts are aligned with the worm shaft. 7. After precise alignment, each member must be securely bolted and if possible doweled in place. Doweling will assure exact repositioning if ever removed. It is essential that a gear unit be securely bolted down to the foundation using bolts of proper diameter to fit the mounting holes. 8. After the screw jacks, bevel gearboxes, couplings, connecting shafts are installed and aligned, there should be no signs of binding or misalignment. 9. Couplings and connecting shaft are the responsibility of the customer and are not provided by Jacton side, unless special requirements in your purchase order. 10. Caution must be taken when operating your jack at either extreme of travel. If possible, hard external stop nuts should be provided. 11. If operating at the upper limits of the screw jack capacity, don t stop the downward travel of the jack by running the lifting screw attachments or the load against the gearbox without checking with Jacton side, as serious damage to the internal mechanism may result. 12. The customer is responsible for providing mechanical stops and limit switches for control of the prime mover. None are included unless special requirements in your purchase order. If limit switches are furnished by Jacton, normally, we install limit switches for controlling full travel stroke, also following customers special requirements. The foundation of the screw jack is critical to insure alignment. Mount the jack and check that the axis of the lifting screw is parallel to the movement of the load and centered with respect to the load. Shim under the base to achieve this if needed. Both eccentric load or side load will cause premature wear 29
and possible bending and failure of the screw jack. Once the alignment is correct hand tighten the mounting bolts. The next step is to align the input shaft with the worm shaft of the screw jack. This alignment can be just as critical to proper operation. Test the alignment by rotating the shafts by hand and fully extend the lifting screws. If the hand operation turns freely and the other components of the system are in alignment, tighten the mounting fasteners and attach the load to the screw jack. Start-up should be and break-in periods of several minutes with careful observation are required. Any vibrations, binding or excessive amperage draw of motors is reason to shut down and repeat the entire alignment procedure. Finally the lifting screw should be re-greased with a light film, and the screw jack gearbox be checked that it is full of grease. Troubleshooting Your screw jack will perform satisfactorily if the suggestions described in the booklet are carefully followed. It is estimated the approximately 98 percent of screw jack failures can be attributed to improper lubrication, misapplication and misalignment. Trouble Inspection Point Solutions 1. Jack Overload Reduce load or replace with unit of sufficient capacity Gearbox Failure Jack should be supported over entire 2. Improper Support base area, not just at bolt hole locations. 3. High Shock Select larger Unit 4. Uneven Bolting Torque Take up evenly on mounting bolts Rigid Couplings can cause shaft Failure. 1. Type of Coupling Replace with coupling which will provide adequate flexibility and lateral float 2. Coupling Alignment Re-align as required 3. Excessive Overhung Load Check Jack for allowable loads 4. Jack Overload See Gearbox failure #1 5. Shock Loading Install coupling capable of absorbing shock and if necessary replace with jack Worm Shaft Failure of sufficient capacity. Shock loads can significantly increase apparent dead weight 6. Ganging Jacks If several jacks are in-line, the worm shaft of the first jack will be subjected to the combined torque of all the jacks. If this torque exceeded 300% of the rated input torque you must replace with a larger jack 30
Bearing Failure Worm Gear Failure Lifting Screw Failure 1. Jack Overload See Gearbox failure #1 2. Coupling Alignment See Worm Shaft Failure #2 3. Excessive Overhung Load See Worm Shaft Failure #3 Adjust spacing between connecting 4. Coupling Lateral Alignment shafts to relieve end pressure 5. Bearing Adjustment Bearings must be preloaded Proper levels and grade must be 6. Bearing Lubrication maintained at all times 7. Shock Loading See Worm Shaft Failure #5 1. Jack Overload See Gearbox failure #1 2. Load Screw Alignment Lifting Screws must be perfectly plumb 3. Lubrication See Bearing Failure #6 Reduce the number of cycles per hour 4. Duty Cycle Limit Exceeded or reduce the load. Contact factory for the maximim allowable cycles per hour 5. Side load Eliminate side load 1. Jack Overload See Gearbox failure #1 2. Load Screw Alignment See Worm Gear Failure #2 3. Side Load See Worm Gear Failure #5 Lubrication The lubricant should not be corrosive to worm gear, ball or roller bearings and must be neutral in reaction. The lubricant must not contain any contamination that may be detrimental to operation of the screw jack. The lubricant must have resistance to oxidation and must be non-channeling. Operating temperatures must be considered when selecting a lubricant for a screw jack. We recoended the following extreme pressure greases or their equivalents. For applications outside these limits contact Jacton. The screw jack normal working temperature -20 deg. C ~ +80 deg. C, Filled with NLGI EP 1 or 2 grade grease, Special working temperature, need special grease, please contact Jacton. Jacton screw jacks are lubricated prior to shipment. Lubrication inspection is recoended at regular intervals. Intervals are determined by the duty cycles of the screw jack, but should be performed a minimum of once every two months. Each screw jack is furnished with a grease nipple. The screw jack should be filled with grease until lubricant begins to seep from the lifting screw opening. For the screw jack is equipped with boots, remove the boot at the jack before you check for proper grease levels. Severe operating conditions may require more frequent lubrication. Lifting screw must be checked regularly to insure that they are adequately lubricated. This is especially critical for the rotating design screw jacks where no lubrication is deposited because the lifting screw does not translate through the screw jack gearbox into the protective pipe. 31
Maintenance Instructions All mounting bolts must be retightened after a short period of operation. Under extreme operating conditions, the wear on the worm gear must be checked at shorter intervals, depending on the power-on time, by inspecting the play in the thread. The worm gear must be replaced if the axial backlash with a single-start thread is more than one-quarter of the thread pitch. After checking the wear, screw jack should be re-assembled by a fitter. Check carefully that rotation is smooth and light and free from axial play. The Lifting screw must be kept free of contaminants and should be lubricated. If possible, lifting screw should be booted or returned to retracted position when it's not in use. Along with periodic inspection, check the alignment of the lifting screw to the load. Misalignment will cause premature wear and possible failure. The load should be centered on the axis of the lifting screw and motion should be parallel to the axis of the lifting screw. The power output shafting must be aligned with respect to the screw jack input shaft. Binding during rotation will cause premature wear. After the screw jacks, connecting shafts, couplings, bevel gearboxes and gear reducers are coupled together in a system, it should be possible to rotate the shafts to fully extend the unloaded screw jacks by hand. The screw jacks are lubricated by the Jacton and are ready for operation on delivery. The translating screw configurations must be lubricated via their grease nipples with one of the greases specified below at intervals of 30 50 operating hours. The lifting screw should be cleaned and greased at the same time. We recoend that the screw jack gearbox be cleaned to remove old grease and refilled with fresh grease after every 600 operating hours or every 18 months. The screw jacks can disassembly and assembly easily: 1. dismount the screw jack and clean. 2. disassemble the lifting screw and lifting screw protective pipe (only for translating screw). 3. Remove locking screws for screw jack gearbox cover. 4. Wash out the screw jack gearbox and components with a suitable wash medium. 5. Refill with grease 32
Frequently Asked Questions What is the difference between an acme screw jack and a ball screw jack? The acme screw jack uses an acme threaded screw that is completely self-locking, meaning it will hold its position without a brake mechanism or locking systems. Ball screw jack use ball screws to convert rotary motion to linear movement, and require approx. 1/3 the horsepower compared to a acme screw jack. Due to the efficiency of the ball screw, brake mechanism must be used to stop and hold the load screw in position. Brake mechanism is also recoended for use on any screw jack if vibration is present. Why use an acme screw jack and a ball screw jack? One type of screw jack is usually better suited to the operating conditions. Typically, fast travel speed and frequent cycle times may be more suited to a ball screw jack, particularly as the load approaches the rated capacity of the screw jack. High load at slow travel speed, less frequent cycles and the ability to hold the load in position when the system is at rest may be better suited for an acme screw jack. How do I operate the screw jack? Most screw jacks are operated by electric motor, but air motors and hydraulic motors can also be used. Hand wheel or crank handle can be used for manual operation. Can I use a larger motor than required in specifications? Yes, but it is not recoended. The screw jack or jack system components could be damaged if an oversize motor is used. Travel limit switches control must be used for each end of travel to stop the motor. If using solid mechanical stops, screw jack components can be subject to shock load conditions and oversize motors can cause catastrophic failure of stops and other components. How do I stop the screw jack at the travel limits? Limit switches or other controls must be used to shut off the motor when the screw jack has reached its full extended or retracted position. Solid mechanical stops are not recoended. Their continued use can cause severe damage to the screw jack. Can different size screw jacks be used in the same system? Yes, as long as the equal travel length per full turn of worm shaft input. This is sometimes done to accoodate varying load conditions. What is the screw jack system efficiency? 2 screw jack system efficiency is 95%, 3 screw jack system efficiency is 90%, 4 screw jack system efficiency is 85%, 6 screw jack system efficiency is 80%. Bevel gearbox efficiency is 98%. Single reduction helical gear reducer efficiency is 98%, Double reduction helical gear reducer efficiency is 97%. Worm gear reducer efficiency is horsepower out x 100 / horsepower in 33
What is the maximum input speed? Jacton screw jack can be run at 1500Rpm. A gear motor, helical gear reducer, or a worm gear reducer is used to reduce the input Rpm to the screw jack to provide the required travel speed of the lifting screw. Many Jacton screw jacks can be driven directly by 1500Rpm and 900Rpm electric motors. Electric motors and reducers are available mounted directly to many Jacton screw jacks models. What causes heat build up in the screw jack? The screw jack is a mechanical gearbox assembly. The friction of the worm and worm gear, lifting screw and worm gear, bearings and seals generate heat while the screw jack is operating. The combination of travel, loading, and input speed all affect the temperature rise of the screw jack. Jacton screw jack sizing calculations take these variables into account to insure that you select the right screw jack model for your application. What is the screw jack load capacity and travel? This is based on the relationship of the lifting screw diameter and the length. Lifting screws in tension are rated for the full capacity of the screw jack, regardless of length, providing they do not rotate faster than the critical speed. For the lifting screw in compression, capacity is limited by the screw jack s permissible buckling load. The permissible buckling load of a lifting screw is reduced as the lifting screw gets longer. Use the maximum extended lifting screw length when using the permissible buckling load charts to determine screw jack load capacity. How do I determine the full-extended lifting screw length? The extended lifting screw length is normally equal to the travel stroke. If screw jack is equipped with bellows boot and stop nut, must be added the bellows boot full retract length and the addition stop nut or special closed height. These must be increased the extended lifting screw length. For inverted screw jack, the thickness of the mounting structure must be included. This total extended lifting screw length should be used when determining the permissible buckling load of the screw jack. Should the load being positioned be guided? It is highly recoended that the load be guided, however, it is not necessary. A guided system will provide more column stability and allow longer screw jack travel. Column length is greatly reduced on unguided systems. External load forces coon with unguided systems are detrimental to the life and operation of the screw jack. Can the screw jack withstand side loading or a bending moment? Yes, but this is not recoended. Consult Jacton if this condition will be present. These types of loads apply greater forces on the screw jack and housing assembly causing premature wear. Guides are highly recoended and should be used to eliminate side and bending loads. Can the screw jack withstand shock loading? This is not recoended. Oversized screw jacks are required to handle shock loads. Solid thrust bearings are also available in many screw jack models when constant vibration and shock are present in an application. 34
What is the difference between upright and inverted screw jack configurations? The difference between an upright and an inverted screw jack is the location at which the lifting screw exits the jack relative to the jack gearbox. For example, an upright screw jack s lifting screw exits the jack opposite the gearbox. An inverted screw jack s lifting screw exits the jack on the same side as the gearbox. The choice between inverted and upright screw jack is dependent upon the application. Note: An upright screw jack mounted upside down is still referred to as an upright screw jack. How is the linear travel speed calculated? Each screw jack has an inherent number show lifting screw travel per full turn of worm shaft input. The result of the screw jack is equal to the lifting screw pitch divided by worm gear ratio. For example, JT-10T model screw jack, screw pitch 8, high worm gear ratio 1/8, the lifting screw travel is 1 per full turn of worm shaft input. If 900Rpm is applied to the worm shaft, the linear travel speed is 900Rpm multiplied by 1/r, equal to 900 millimeter per minute. Are screw jacks lubricated prior to shipment? All Jacton worm gear screw jacks and ball screw jacks are lubricated with an extreme pressure NLGI grade #1 or 2grease before leaving the factory. Bevel gear screw jacks are lubricated with NLGI grade #1 grease or VG220 gear oil. The upper bearing and jack screw are grease lubricated while the remaining internal components are oil lubricated. They are grease lubricated prior to shipment. What electric motors options are available? Electric motor options vary among product lines. Customers can use AC 3-phase motor, AC single-phase motor, DC motor. Standard voltage of China is 380V/220V, 3-phase, 50Hz, or 220V, single-phase, 50Hz. Customized international voltage motors like America 110V-single phase-60hz, 240V/480V-three phase-60hz, other voltages 230V/240V-single phase-50hz, 400V/415V/440V-three phase-50hz etc. Are screw jacks corrosion resistant? Stainless steel screw jacks are inherently corrosion resistant. All exposed surfaces are stainless steel and aluminum bronze. Most other screw jacks can be modified with special finishes, coatings, and seals. Can bellows boots be supplied for an screw jack model with inverted screw? Yes, but allowance must be made in the length of the lifting screw for both the closed height of the boot and structure thickness. Since we can make no provision for attaching a boot on the underside of your structure, we suggest that a circular plate similar to the lifting screw top plate be welded or bolted to the bottom of your structure supporting the screw jack, thereby making it possible to use a standard bellows boot. Is there backlash between the lifting screw and worm gear? Yes. This is necessary to allow for sliding or rolling action of the lifting screw through the worm gear. Anti-backlash nut screw jack is available when the backlash needs to be minimized. Input torque requirements are greater for anti-backlash nut screw jack. 35
How is the lifting screw protected? Standard translating screw jack is fitted with a lifting screw protective pipe that stores the lifting screw when the screw jack is in the closed position. Bellows boot is available and recoended to protect the lifting screw in the extended position. Double bellows boots are required for rotating screw jack with traveling nut. How do I attach the load to be positioned to the lifting screw? For translating screw jack, the lifting screw has a standard threaded end that can be used to attach the load, top plate, clevis end, plain end and forked head are also available. For traveling nut design, the traveling nut has a flange with mounting holes. The screw jack gearbox has a mounting base and is also available with a clevis mount for double clevis requirements. Will the lifting screw rotate? Yes. You need to prevent the lifting screw from rotating to produce linear motion. The lifting screw will not rotate in a multiple screw jack system with all the lifting screws attached to the same structure. If rotation of the screw cannot be prevented in the application design, a keyed screw configuration is available for either the acme screw jack and ball screw jack. Input torque will increase for keyed screw jack and the capacity may be reduced to 25% of rating. What is the maximum and minimum operating temperature? Standard Jacton screw jacks are designed to operate at maximum 80 deg.c (185 deg.f) ambient temperature. For higher temperatures, special grease and seals are required, contact Jacton of these special requirements. Minimum minus 20 deg.c (minus 4 deg.f) ambient temperature. For lower temperatures, special grease and seals are required, contact Jacton of these special requirements. How do I lubricate a screw screw jack? Use the proper grease. Fill the gearbox by pumping grease into the grease fittings supplied in the screw jack housing. The lifting screws should have grease applied directly to them with a rag or paintbrush. This must be done as part of a regularly scheduled maintenance program. 36
Company History In 1997, Established Jacton Hardware Fabrication Plant, mainly processing kinds of hardware following customers requirements. Occupied 500 square meters. In 2000, Established domestic sales department, started to develop local market, mainly processing gear transmission parts such as worm and worm gear, acme threads screw, square threads screw and acme lead screw nut. Meanwhile, sales also sell straight bevel gear and spiral bevel gears for customers. In 2002, According to some regular customers of steel plants and machines manufacturers, which used Taiwan screw jacks and miter gearboxes, due to long delivery and high price, would affect the normal operations. Jacton Hardware Fabrication Plant started to processing JT acme screw jack and JT miter gearbox following above customers samples. In 2003, Established engineering department, research and development others models of JT acme screw jack and JT miter gearbox, and draw some factory production drawings and local sales' customers drawing with 2d autocad software. In 2005, According to local market demands, Jacton Hardware Fabrication Plant is coitted to research and development JB/T8809-1998 standard JTW worm screw jack, JTM machine screw jack, JTB ball screw jack and JTP cubic body miter gearbox. In 2006, Because of local markets fiercely competitive. Established Hongkong office-jacton International Limited with own US dollars and EURO account. Established international sales department, focused on overseas markets. Meanwhile, "JACTON" as company only brand. In 2008, According to intl sales market report, cubic body screw jacks and another type cubic body miter gearboxes are very popular in Europe and America markets. After managements meetings, we started to develop JTC cubic screw jack, JTS high speed bevel gear jack, JTV cubic body miter gearbox and JTA corrosion resistance aluminium body miter gearbox. In 2009, Jacton Hardware Fabrication Plant extension, occupied 5000 square meters. Company improves the processes and products through technology investment, brings in advanced technology, production and testing equipment. In 2010, Jacton Hardware Fabrication Plant Passed ISO9001:2008 quality management system, we are strictly implement the work flow of ISO9001:2008 certifications, which ensures oversea and local customers are satisfaction with our screw jacks and miter gearboxes and fast delivery time. In 2012, In order to facilitating management, according to management decisions, sales department and design department moved to Taibao business building. Meanwhile, Jacton Hardware Fabrication Plant changed to be Dongguan. 37
Contact Us (Head Quarters) 1&2 Floors, Building F, Baisheng Industrial Areas, No.34, Yongjun Road, Datang, Dalingshan, Dongguan, Guangdong, China Phone: 86 769 81585810 Mobile: 86 189 25569548 Jacton International Limited (Hong Kong Branch) Office 17,9/F.,Tower A,New Mandarin Plaza,No.14,Science Museum Road, Tsimshatsui,Kowloon,Hongkong Tel: 852-2793-5511 Fax:852-3590-2333 (Sales Dept. & Design Dept.) 1118, Taibao Business Building, No.1 Langwei Rd, Xinan, Changan, Dongguan, Guangdong, China Phone: 86 769 81585852 Fax: 86 769 81620195 Contact Us General Enquiries: sales@screw-jack.com jactonjack@gmail.com Online Skype: jactonjack (Warren) Online Skype: jactongearbox (Abby) Website: Urgently required, please directly make a call to Warren +86 13532830851 38