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Screw Jack

Screw jacks are essential components in industrial and mechanical systems where controlled linear movement and precise load handling are required. They provide a dependable and robust method for lifting, positioning, or adjusting heavy equipment in a wide range of applications.

Polimak’s screw jack systems are designed to offer safe and efficient performance across both light-duty and heavy-duty applications. Their adaptability makes them suitable for single-unit use or integrated into multi-jack arrangements for synchronized motion. The main capabilities and common applications are listed as follows:

Key Functions of Screw Jacks:

• Linear Motion Conversion: Converts rotational motion into precise linear movement, suitable for applications requiring exact positioning.

• Heavy Load Handling: Capable of lifting loads ranging from a few kN to several thousand kN, depending on the system configuration.

• Multi-Jack Synchronization: Multiple screw jacks can be linked mechanically or electrically for uniform movement in large systems.

• Manual or Motorized Operation: Can be operated using handwheels for manual control or electric motors (AC/DC) for automated systems.

• Positioning Accuracy: Offers high precision in movement, making them suitable for assembly lines, stage mechanics, and adjustable platforms.

Common Applications of Screw Jacks:

• Industrial Machinery Setup: Used to lift and set the position of heavy components during installation or maintenance.

• Construction Platforms: Provides adjustable support for temporary structures or platforms on irregular surfaces.

• Vehicle Maintenance: Supports lifting tasks for inspection, repair, or assembly in automotive and aerospace sectors.

• Material Handling Systems: Integrated into conveyor systems or processing equipment for height adjustment or positioning.

• Stage and Theatre Equipment: Allows precise elevation and lowering of platforms in performance venues.

Screw jacks combine mechanical simplicity with powerful output, making them a practical and reliable solution for demanding motion and lifting tasks.

SCREW JACK WORKING PRINCIPLE

Understanding how a screw jack operates is key to understanding its effectiveness in lifting and positioning heavy loads. The primary components that make up a screw jack include:

• Trapezoidal lifting screw (also known as the lead screw): A threaded rod that moves up or down to lift or lower the load as it rotates.

• Worm screw: A helical gear that transmits rotational motion from the motor or handwheel to the worm gear.

• Worm gear: Engages with the worm screw to convert rotational motion into the linear movement of the lead screw.

• Gear housing: The protective casing that holds the worm screw and worm gear, ensuring proper alignment and smooth operation.

The operation of a screw jack involves several key steps:

• The worm screw is turned either manually using a handwheel or powered by an electric motor.

• As the worm screw rotates, it drives the worm gear. This, in turn, causes the lead screw to move in a linear direction, either upwards or downwards.

• Several factors influence the speed at which the lead screw moves, known as the feed rate. These factors include the rotational speed of the worm screw, the number of teeth on the worm gear, and the pitch size of the lead screw.

• This precise conversion of rotational motion into linear motion allows for controlled lifting or lowering of heavy loads with high accuracy and safety.

In some models of jackscrews (T-Travelling Nut Type):

• The lifting screw does not move up and down but instead rotates around its axis.

• A lifting nut (also known as a traveling nut) moves along the lead screw to provide the lifting action.

• The lifting nut is typically made of bronze to reduce friction and ensure smooth movement.

TYPES OF SCREW JACKS

Polimak offers screw jacks in three different types:

1. Travelling Screw Type

2. Travelling Wedge Screw Type

3. Travelling Nut Type

V-Travelling Screw Type  

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K-Travelling Wedge Screw Type  

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T-Travelling Nut Type  

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TYPES OF SCREW JACK ENDS

Plain End

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Clevis End

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Flange End

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Travelling Nut

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Applications Across Industries

Screw jacks have become an essential component in many sectors thanks to their robust performance and adaptability. They are widely used for lifting, aligning, positioning, and maintaining stable load positioning. Known for their dependable performance and accurate synchronization, screw jacks can offer improved control compared to pneumatic and hydraulic systems. This makes them the preferred choice for applications requiring fine adjustments and consistent performance.
Screw Jack Applications

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FAQs

Everything you need to know about the Screw Jack. Can’t find the answer you’re looking for? Please chat to our friendly team.
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• A screw jack is a mechanical device designed to transform rotational motion into precise linear movement.

• It operates by turning a screw shaft. This rotation raises or lowers a load attached to the jack’s lifting mechanism.

• This device is highly versatile and can handle heavy, moderate, or even delicate loads depending on the design and size of the application.

• Screw jacks are commonly used for lifting, positioning, aligning, and holding loads securely in place.

• They find application across a broad spectrum of industries, including manufacturing, construction, automotive, aerospace, and material handling.

• Known for their reliability and mechanical simplicity, screw jacks offer controlled motion without requiring complex hydraulic or pneumatic systems.

• Many screw jacks feature self-locking capabilities, ensuring safety by preventing the load from slipping or moving unintentionally.

• Their compact design and ease of integration make them ideal for both stationary and mobile equipment requiring precise linear actuation.

• A lead screw, also known as a translating screw or power screw, is a mechanical component that transforms rotary motion into straight-line movement.

• It consists of a threaded shaft and a corresponding nut that travels along the threads as the shaft rotates.

• Lead screws are widely used in linear actuators to provide precise, controlled positioning and movement.

• They are preferred in applications where accuracy, repeatability, and smooth motion are essential.

• Common industries utilizing lead screws include robotics, CNC machinery, medical devices, and automated manufacturing systems.

• Lead screws can handle various load capacities depending on their size, thread design, and material.

• They can generate high levels of force efficiently, typically without needing extra gear systems.

• Many lead screws feature self-locking properties, which help maintain position without back-driving under load.

• Power Mechanism:

• Mechanical jacks operate using screw threads to convert rotational input into linear lifting motion.

• Hydraulic jacks use pressurized hydraulic fluid to provide force and lift loads.

• Load Holding and Safety:

• Mechanical jacks are generally self-locking. They can hold a load in position without continuous power or external braking systems, which enhances operational safety.

• Hydraulic jacks require valves to maintain pressure. If pressure is lost or leaks occur, the load can descend unexpectedly.

• Precision and Control:

• Mechanical screw jacks offer fine control over movement, making them ideal for applications where accurate positioning is essential.

• Hydraulic jacks provide faster lifting but with less precise control. This can be an obstacle in applications that demand exact placement.

• Load Capacity and Speed:

• Hydraulic jacks generally support higher load capacities and faster lifting speeds, making them suitable for heavy-duty tasks.

• Mechanical jacks lift at slower speeds and may handle lighter loads but provide more control and reliability.

• Maintenance and Reliability:

• Mechanical jacks require minimal maintenance. Therefore, they are less prone to failure, as they do not rely on fluids or seals.

• Hydraulic jacks involve more complex systems that need regular inspection and maintenance to prevent leaks and pressure loss.
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APPLICATIONS Screw Jack Applications Polimak Linear Motion Technologies is committed to delivering high-performance solutions that support critical operations across a wide range of sectors. From complex machinery to structural systems, our products are designed to meet the demanding requirements of modern industries with efficiency and precision.We specialize in a wide range of screw jacks engineered […]

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OVER 40 YEARS OF SERVICE About Us Polimak is a leading engineering and fabrication company, specializing in bulk solids handling technologies for over four decades. Our wide range of versatile bulk material handling machinery is appropriate for value-added logistics as well as handling powders, granules and pellets in the food, chemical, plastics, minerals, and agriculture […]

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These valves are typically actuated by pneumatic actuators and are used to automatically open and close the product flow to discharge material to downstream equipment.
Installed below silos or hoppers, these valves are used for maintenance operations of equipment such as rotary valves, screw feeders, etc., that are positioned below the butterfly valve.
These valves are typically actuated by pneumatic actuators and are used to automatically open and close the product flow to discharge material to downstream equipment.
In this design, the butterfly valve is sandwiched between two flanges. Rubber sealing at both faces of the valve provides a tight seal between the flanges and the wafer butterfly valve.
One side of the valve has a bolted flange connection, while the other side features a built-in short pipe designed for fixing a flexible sleeve.
These valves have bolted flange connections on both sides, making them suitable for installation on silos, hoppers, screw feeders, and similar applications.
Bulk tanker trucks or open trucks can be filled with powdered materials delivered within FIBC bags. These systems generally consist of bulk bag discharging station, mechanical or pneumatic conveyor and loading bellow. Big bag discharge station transfers the bulk solid from big bag to conveying system. Conveying system transfers it to truck loading area. And loading bellow is used to fill tanker truck without any dust emission. Since truck loading operations are done within limited time, high capacity big bag discharge systems and bulk material conveying systems are used. For short distances, screw conveyors are preferred to transfer material from big bag discharge station to truck loading chute. For long conveying distances, pneumatic conveying systems provide better service. There may exist a storage hopper or silo above bulk truck loading bellow to compensate material flow between inlet and outlet. Bulk bag discharge and truck filling systems have automatic control system that monitors product level in truck and operates all equipment accordingly. Optional weighing system can be added to measure the amount of material that is filled to truck.
Big bag discharge systems can deliver dry bulk solids in powder and granular form to weighing and batching systems. The loading hopper of the weighing system should remain full during dosing and batching. Big bag discharge systems can monitor the product level in the loading hopper and maintain a constant level automatically. Depending on the dosing speed and conveying distance, mechanical conveying systems or pneumatic loading systems may be used. Dust collectors can be employed to prevent dust emissions during hopper loading, especially for materials with high dust content.
Dry bulk packaging systems are used to fill powdered or granular materials into bags, drums, jars, sacks, etc. Bulk materials delivered in big bags must be transferred to packaging machines without interruption. The loading hopper of the packaging system should remain full during the filling and packaging process. Big bag discharge systems can monitor the product level in the loading hopper and maintain a constant level automatically. Depending on the packaging speed, mechanical conveying systems or pneumatic loading systems can be selected. Dust collectors can be used to prevent dust emissions during hopper loading, especially for materials with high dust content.
Mixer automation systems are used to mix dry bulk solids according to specific recipes. Raw materials delivered in FIBC bags can be transferred to mixing units through a combination of conveying equipment and bulk bag discharge systems. Depending on the type of application, pneumatic conveying or mechanical feeding systems can be used to fill mixers. Big bag discharge stations can be manufactured with built-in dosing systems. The amount of raw material to be loaded into the mixer is automatically controlled with the help of a weighing and dosing system. Dust collectors can be used to prevent dust emissions during the mixer filling process.
Bulk material stored in big bags can be automatically filled into small bags. Big bag discharge systems come with optional built-in bag filling units. For low filling capacities, these units are installed below the big bag discharge hopper, providing a practical and cost-effective solution. Both big bag discharging and bag filling operations can be handled by a single, compact system. For higher bag filling needs, bag filling machines are installed near the bulk bag discharge stations. Pneumatic conveying systems or mechanical conveyors can be used to transfer bulk material from the FIBC bag discharge station to the bag or sack filling system.
Mechanical conveyors can be used for silo loading from big bag discharge stations. Screw feeders, bucket elevators, rotary valves, or chain conveyors are connected to big bag discharge stations to fill silos. The selection of conveying equipment directly depends on the conveying distance, height, transferred material, and capacity. Bucket elevators are preferred for high silos, while screw feeders are preferred for shorter silos and short distances. The big bag discharge system can be installed on top of the silo for faster filling. In this case, rotary valves or butterfly valves are better choices as they provide simple flow control. Dust collection systems may be required depending on the dust content of the bulk solid. During silo loading, air content in the silo escapes to the atmosphere and carries some dust along with it. Vacuum fans and jet filters in dust collectors prevent dust emissions into the environment. The collected dust is sent back to the silo, thus preventing product loss.
Pneumatic conveying systems installed after bulk bag discharge units transfer bulk material through conveying pipelines to fill silos. This configuration is useful in applications where high transfer rates and long conveying distances are needed. In production lines where raw materials are stored in warehouses far from storage silos, bulk bag discharge stations can be installed close to the warehouses, and pneumatic conveying systems are used to fill silos from long distances. This design reduces the need for forklifts and cranes for bulk material transfer on the production site and increases overall efficiency.

Pneumatic conveying systems used for silo loading utilize blower pumps or compressors. Motor power, pipeline diameter, and equipment selection depend on the type of bulk material, transfer distance, silo height, and transfer capacity. Level sensors, jet filters, and other equipment are installed on storage silos to ensure the proper operation of the silo filling system.
Pneumatic conveying systems installed after bag dump units transfer bulk material through pipelines to fill silos. This configuration is ideal for applications requiring high transfer rates and long conveying distances. In production lines where raw materials are stored in warehouses far from storage silos, bag dump stations can be installed close to warehouses, allowing pneumatic conveying systems to transport materials over long distances. This design reduces the excessive use of forklifts and cranes for bulk material transfer within the production site, improving overall efficiency.

Pneumatic transfer systems used for silo loading utilize blower pumps or compressors. Motor power, pipeline diameter, and equipment selection depend on factors such as the type of bulk material, transfer distance, silo height, and transfer capacity. Level sensors, jet filters, and other equipment are installed on storage silos to ensure the proper operation of the silo filling system.
Mechanical conveyors can be used for silo loading from bag dump stations. In this configuration, screw feeders, bucket elevators, rotary valves, or chain conveyors are connected to bag dump stations to fill silos. The selection of conveying equipment depends on factors such as conveying distance, height, material properties, and capacity. Bucket elevators are preferred for high silos, while screw feeders are ideal for shorter silos and short distances. Bag dump systems can be installed on top of the silo for faster filling. In such cases, rotary valves or butterfly valves are better choices as they provide simple flow control.

Dust collection systems may be required depending on the dust content of the bulk solid. During silo loading, air inside the silo escapes to the atmosphere, carrying dust particles with it. Dust collectors equipped with a vacuum fan and jet filter capture airborne dust. The collected dust is returned to the silo, preventing product loss and ensuring a cleaner environment.
The inlet skirt is an optional feature designed to extend the lifespan of the flexible connector sleeve. Its upper portion is attached to the outlet port of the upstream equipment and extends down into the bin activator’s inlet port. The primary function of the inlet skirt is to serve as a protective shield, safeguarding the flexible connector seal from wear and damage.
A vibratory motor is externally mounted to the bin activator. When powered, the motor generates vibrations that facilitate a steady flow of dry bulk materials within the system. Depending on the application requirements, one or two vibratory motors can be installed externally.
To accommodate a bin activator, the cone of a silo must be shorter than usual, resulting in a wider outlet. A flange supplied with the bin activator is separately welded to the silo’s outlet, slightly above the opening, at the production site. Once installed, the vibrating bin discharger is securely bolted to the flange, ensuring a stable and reliable connection.
Special spring suspension links and an engineered polymer seal work together to create a flexible connection between a vibrating bin discharger and the equipment positioned above it.

The proper design and installation of the polyurethane seal prevent it from slipping off and ensure a secure seal, eliminating the risk of dry bulk material leakage. Additionally, the seal offers high stress resistance and long-term durability, withstanding stresses caused by motor vibrations, pressure conditions, and other operational factors.

Externally installed spring suspensions provide full resilience to the vibrations of the cone head. They ensure that the generated vibrations affect only the cone itself rather than the upstream equipment structure.
An internally tapered, conical-shaped baffle plate is positioned at the center of the bin activator’s diameter. The baffle is rigidly attached to the equipment body using structural steel components. It facilitates bulk material flow from upstream equipment by directly inducing vibrations into the material.

A secondary deflector plate reduces the weight of the bulk material in the lower portion of the bin activator by acting as a wedge beneath the material, directing it around the areas adjacent to the cone’s surface.

Polimak baffle plates are available in various configurations, including convex and cone plates, and in different angles (15°, 30°, 45°, or even 60°) depending on the flow characteristics of the handled bulk material and the specific application requirements.