1：What is the difference between a trapezoidal screw jack and a ball screw jack?
The trapezoidal screw jack uses an acme threaded screw that is typically self-locking, meaning it will hold its position without a brake. Ball screw jacks use ball screws to convert rotary motion to linear movement and require 1/3 the horsepower compared to a trapezoidal screw jack. Due to the efficiency of the ball screw, brakes must be used to stop and hold the load screw in position. Brakes are also recommended for use on any jacks if the vibration is present.
2：What do I need to consider when order a bellows boot to protect the jack lifting screw?
When a bellows boot is ordered for a jack, the closed height dimensions may change. When ordering a bellows boot for an inverted jack, need to consider the closed height of the bellows boots and structure thickness. Usually, under fully retracted, the bellows boots closed height =0.15* travelling strokes. For example, upright mounting, request 1000mm stroke, plus rubber bellows closed height 0.15*1000=150mm. So need to order at least 1150 mm stroke with rubber bellows.
3: How is the lifting screw protected?
For translating screw jacks are fitted with a steel protective tube that stores the lifting screw when the screw jack is in the closed position. Rubber bellows are available and recommended to protect the lifting screw in the extended position. Two rubber bellows may be required for rotating screw jacks with traveling nuts.
4: Can the screw jack work at high or low temperature?
Using standard greases and oil seals, the screw jack working temperature is from -15 degrees to 80 degrees. At present, we have a customer use the screw jack at 300 degrees with special grease and seals. Any special working temperature, please tell the SIJIE engineer team before selecting models.
5: What is the duty cycle?
The duty cycle is the relationship between operation time and rest time. The allowable duty cycle for screw jacks is based upon several application variables such as load, speed, and temperature. Usually duty cycle at 30-minute intervals for SJW machine screw jacks and SJC worm gear screw jacks are within 20% ED, SJB machine ball screw jacks and SJD worm gear ball screw jacks is within 30% ED.
6: Which type of screw jacks require a brake motor?
All SIJIE trapezoidal screw jack has the self-locking function, so it is safe for holding the load and accurate positioning without a brake motor. The Brake motor is recommended for all the ball screw jacks and very large load trapezoidal screw jack applications.
7: What is the maximum input RPM for jacks and bevel gearboxes?
Limited to 1500 RPM for the screw jacks shaft input. Maximum input RPM may be slower than 1500 RPM depending on the dynamic load and other factors specific to the applications. The bevel gearboxes offer the maximum 2000 RPM shafts input.
8: How much backlash is in a worm gear screw jack?
There are two types backlash for a worm gear screw jack: worm gears to worm shafts backlash( usually 0.1mm to 0.3mm for a new jack and it will change with working.), and lifting screw to guide ring backlash( typically up to 0.5mm for a new jack),this backlash also called lateral backlash.
9: How to reduce the backlash of worm gear screw jack?
With the wear between worm gears and worm shafts, the backlash of the worm gear screw jack will be larger. Our Anti-backlash design can adjust the screw jack’ backlash.
10: What is the amount of lead error for a lifting screw?
We process the trapezoidal lifting screws according to DIN103 standard and ball lifting screws according to the 68051T3 standard. The cumulative error is up to 0.1mm/300mm for machined trapezoidal screws and 0.03mm/300mm for ball screws.
11: Which type of motor is available for machine screw jacks?
Our machine screw jacks offer the flange design which is available for IEC motors and NEMA motors. Customers can use AC 3-phase, AC single-phase, DC motors, international voltage motors, and others.
12: How to calculate the electric screw jacks lifting speed?
The electric screw jacks lifting speed are related with input motor RPM, gear ratio and pitch.
V(mm/min)= RPM
13: Are screw jacks and bevel gearboxes lubricated prior before shipment?
All SIJIE machine screw jacks, machine ball screw jacks, worm gear screw jacks, worm gear ball screw jacks, and bevel gear screw jacks are lubricated with the 0 # or 1 # lithium grease before shipping. We also add the grease on the lifting screw for lubrication and rust protection.We use the Industrial gear oil in the bevel gearboxes. Because of the gear oil can not for International transport, we remind our customers to add the industrial gear oil into the bevel gearboxes before using.
14: What accessories are available for the screw jacks system?
SIJIE configures screw jacks with components such as bevel gearboxes, motors, couplings, gear reducers, connecting shafts, pillow blocks, hand wheels, and motion control devices. SIJIE is a superior linear motion solutions provider.
15: What are the delivery time of SIJIE screw jacks and bevel gearboxes?
For machine screw jacks and worm gear screw jacks, the delivery time is around 7-15 working days.
For machine ball screw jacks and worm gear ball screw jacks, the delivery time is around 25-30 working days.
For bevel gear screw jacks, the delivery time is around 20-25 working days. For the bevel gearboxes, the delivery time is around 7-10 working days.
16: Can we use a larger motor than permissible max.?
The SIJIE screw jacks permissible max. power is the result of under 20% duty cycle, so we can use a larger motor than permissible Max. if the duty cycle is less than 20%. It is not recommend to use a large motor than screw jacks’ permissible Max. If the duty cycle more than 20%.
17: Are screw jacks and bevel gearboxes are corrosion resistant?
Stainless steel screw jacks and bevel gearboxes 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.
18: Can we make the special industrial applications screw jacks?
We can offer the screw jacks which are used under water, in explosion-hazard areas and radiation-contaminated areas.This screw jacks need special design and special materials. More details, please contact SIJIE engineer team.
19: How to calculated life of machine screw jacks?
There is no formula available to calculate the life of a machine screw jack, it depends on many factors such as working frequency,speed,working Environment,load capacity and others, but we can improve the life of a machine screw jack by regular maintenance.
20: How to calculated life of a ball screw jack?
The ball screw with nut is the main key for the life of a ball screw jack, so we use the famous TBI ball screw. There are many data showing the details of a ball screw with nut calculated life( Please contact us if you need). According to our experience, the ball screw can work 100000 times with 300mm length.
21: When need a stop nut at the end of lifting screw?
The acme screw jack typically has the self-locking function and the ball screw jack operated with brake motor. But for high speed and double lead screw application, customer need a stop nut at the end of lifting screw to prevent the lifting screw from put off.
22: What is rotating screw jack?
A lofting screw keyed to the worm gear as a single unit, forcing the lifting screw to rotate, but not translate. A travelling nut, attached to the load, is driven by the rotation of the lifting screw. This type jack is ideal for applications that can not accommodate a screw protection tube and save enough mounting space.
