Worm Gear Screw Jack Operation Manual

Worm Gear Screw Jack Operation Manual

Caution: Read this manual before installation or operation of JACTON screw jack. Failure to understand this manual, installation or operation screw jack properly could result in damage to the jack and or serious personal injury. 
Do not exceed the jack ratings including design load capacity, travel length, 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 jack mounting holes, at least grade 5 and tightened to the appropriate torque. Mounting bases should be flat and sufficiently strong to support the load. Properly lubricate and maintain the JACTON product. Use the jack only for the intended application. Failure to install, use, or maintain JACTON products could result in product failure and personal injury.
This operation manual is applicable to all jacks models. Note: Information represents typical configuration and may difference slightly from the actual jack being installed or repaired. The maintenance instruction provides recommendations of safe and efficient approach to installation or service repair problems.
When an operating situation occurs, refer to the troubleshooting guide to isolate cause. When applicable, guides are listed by symptom followed with suggestions of probable causes.

Once the source of the problem is identified, consult JACTON engineers for disassembly and re-assembly procedures guides for recommended repair procedures.

General Instruction and Specifications
Your screw jack was manufactured to high quality standards and is designed to provide many hours of service. But certain safety measures and procedures must be followed in handling, installing and servicing the jack to insure long trouble free service.
1. Any obvious or suspected damage to jack during transport from the factory must be immediately reported to JACTON company and the carrier.2. Upon delivery all of the jack should be inventoried to determine if shortages exist. All shortages must be immediately reported to JACTON company and the carrier.
3. The installation jack supplied by JACTON company does not include the services of a field engineer. 
4. The warranty applies only if the jack is operated within the rated capacity and conditions for which the jack was specifically designed. The application design engineer must prevent any destructive conditions for the jacks. Conditions that may be considered destructive are: excessive input speeds, extreme shock loading, mechanical or thermal overloading, exceeding recommended duty cycles, and side loading of the load screw.
5. Installation, maintenance and safety instructions must be given to personnel directly responsible for the installation, maintenance and operation of the jack.
6. In the event that a malfunction of the jack occurs within the warranty period JACTON company must be informed immediately and the jack must be immediately removed from service.

Caution: screw jack is normally self-locking feature. Vibration could cause the screw jack to self lower or creep. In the absence of internal or external stops the load screw can be moved out of the jack base. Your jack base is not equipped with internal stop nuts unless special requirements in your order. Jacks are not meant for personnel support. All applications designed for personnel support must be approved by JACTON company engineers.
The worm gear driven screw jack incorporates a high frequency heat treatment high hardness 40Cr or C45 steel worm which drives a high tensile Phosphor bronze 10-1 or Tin bronze 10-1 worm gear, accurately machined to the high standards of JACTON Company for maximum load carrying capacity and uniformity of motion transmission. All shafts are mounted on heavy duty tapered roller bearings to increase operating efficiency of the drive mechanism. Heavy duty tapered roller bearings are provided to support the rated thrust load of each jack. Housings are made of aluminium, cast iron or ductile cast iron are designed to handle the rated thrust load and torque loads of each jack size.
A protective pipe is furnished which is threaded into the jack in order to keep the load screw threads dust-proof and lubricated. The load screw is made of high quality 40Cr or C45 steel that is ground to size and precision rolled to form the threads. They are well proportioned to handle the maximum lifting force of the jack. Stainless steel or special customized alloy load screws can be provided at an additional cost. The threads of the load screw should be well lubricated and kept free of grit and dirt. Bellows boots can be provided as an accessory to protect the exposed portion of the load screw. In the event of over travel the boots may be crushed. Standard jacks may be operated at a wide range of input speeds. All jacks are recommended based on customer supplied duty cycle requirements.

Installation Instructions
1. Be certain that the rating of the jack exceeds the maximum load that may be imposed upon it.
2. Check that rated input speeds of the jack will not be exceeded. Verify in the jack catalog technical datas pages.
3. The foundation for the jack must be rigid enough to maintain correct alignment with connected machinery and have ample strength to carry the maximum load.
4. The foundation should have a flat mounting surface to uniformly support the jack. The opening for the load screw cover (or load screw) that passes through jack base must be as small as possible to provide jack support over the largest possible area.
5. Check that the method of stopping the screw rotation so translation will occur is sufficiently strong.
6. It is extremely important that the jack be installed so that the load screw is exactly plumb and that all line shafting is 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 jack.
8. After the jack, miter gearbox, couplings are installed and aligned, there should be no signs of binding or misalignment.
9. Shaft coupling guards are the responsibility of the customer and are not provided by JACTON, unless specifical requirements in your order.
10. Cautions must be taken when operating your jack at either extreme of travel. If possible, hard external stops should be provided.
11. If operating at the upper limits of the jack rating, don't stop the downward travel of the jack by running the load screw attachments or the load against the housing without checking with JACTON, 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 travel length. None are included unless specifical requirements in your order.
Important: take up evenly on mounting bolts to avoid damaging the housing.

Cautions:
If limit switches are furnished by JACTON, they are not factory set. Limit switches should be set by carefully moving the set position by hand or jogging the motor. Care should be exercised when operating the jack at the extreme limits of travel.
The foundation of the jack is critical to insure alignment. Mount the jack and check that the axis of the load 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 loading and/or side loading will cause premature wear and possible bending and failure of the jack. Once the alignment is correct hand tighten the mounting bolts.
Next align the input shafts with the worm shaft of the jack. This alignment can be just as critical to proper operation. Test the alignment by rotating the shafts by hand, and fully extend the load 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 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 load screw should be re-greased with a light film, and the jack housing be checked that it is full of grease.

Trouble Shooting
Your jacks 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. 


Lubricant
The lubricant should not be corrosive to gears, 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 jack. The lubricant must have resistance to oxidation and must be non-channeling. Operating temperatures must be considered when selecting a lubricant for a jack. We recommended the following extreme pressure greases or their equivalents. For applications outside these limits contact the JACTON engineers.
The jack working temperature -20 deg. C  to +80 deg. C, NLGI #2 grease, super high/low temperature, need special grease, please contact JACTON engineers.
JACTON jacks are shipped with grease. Lubricant inspection is recommended at regular intervals. Intervals are determined by the duty cycles of the jacks but should be performed a minimum of once every two months.
Each jack is furnished with a grease fitting. The jack should be filled with grease until lubricant begins to seep from the load screw opening. For jacks with boots, remove the boot at the jack before you check for proper grease levels. Severe operating conditions may require more frequent lubrication.
Load screws must be checked regularly to insure that they are adequately lubricated. This is especially critical for the rotating design units where no lubrication is deposited because the load screw does not translate through the housing into the protective pipe.

Assembly Inspection 
Caution: Never perform any work on the jack or associated transmission equipment until the prime travel length cannot be remotely or automatically started. Make sure the load is properly supported before the Jack, brake, or other holding devices are removed. Be sure the area around the Jack is relatively clean to prevent the parts from becoming contaminated, and the machined parts are stored on wooden blocks to prevent damage to the machined surfaces.
1. If possible remove the jack from the structure and inspect the jack on a work bench. If not use cribbing to support the load.
2. Clean the jack of grease, dirt, and foreign material
3. Visually inspect the jack for damage such as cracked, broken or chipped parts, and married surfaces.
4. Using a soft cloth or tape to protect the input shaft, with a pair of pliers or by hand, attempt to turn the input shaft. If it won't turn without extreme effort, total disassembly will be required. Consulting JACTON engineers for the disassembly procedure.
5. Measure the rotary backlash: Rig a positive stop and extend the load screw against the stop. Mark the position of the input shaft. Reverse the rotation of the input shaft until you feel the beginning of the load screw movement. Again mark the position of the input shaft. Measure the angle of this rotation. If the measurement exceeds the 60 degrees then the worm shaft and the worm gear must be replaced.
6. Measure the axial backlash: Extend the load screw against the positive stop. Mark and remove the positive stop. Protect the load screw with a soft cloth or tape, clamp a handle to the load screw and pull the load screw in the direction of the removed stop. Measure the movement to determine the axial movement. If the movement is greater then the allowable limits from the table below the worm gear and the load screw should be replaced.