BALL SCREW JACKS
BALL SCREW JACKS
SERVOMECH screw jacks convert rotary motion into linear motion, ideal for lifting or positioning tasks. They can operate individually or in synchronized systems. Ball screw jacks offer higher efficiency and longer service life than traditional acme screws, with two models available: travelling screw (Model A) and travelling nut (Model B).
The catalogue features three main series of ball screw jacks: MA BS Series for continuous high-efficiency operation, SJ BS Series for intermittent duty cycles, and HS Series for high-speed applications. Each series offers various sizes and load capacities.
Screw jacks include precision worm gearboxes with high efficiency and reduced angular backlash. Components such as bronze wormwheels and hardened steel wormshafts ensure durability and performance.
Guidelines for selecting screw jacks consider self-locking conditions, buckling, critical rotating speed, and lifespan. Detailed technical data is provided for various models and sizes.
Model A and Model B screw jacks are built with robust materials for specific load capacities and speeds. Technical specifications and dimensions are included.
Instructions for installation, maintenance, and lubrication ensure optimal performance and longevity. Each product includes a final test sheet certifying conformity and operational guidelines.
Detailed ordering codes and accessory options allow customization to meet specific application needs.
The document details specifications for components like housing materials, wormwheel, worm shaft, ball screws, and nuts. Housing materials include aluminum alloy, grey cast iron, spheroidal graphite iron, and welded steel. Wormwheels are bronze, and worm shafts are case-hardened steel.
Ball screws and nuts are internally produced, with ball nuts made from case-hardened alloy steel and threaded shafts from quenched and tempered alloy steel. Hardness range for ball tracks and preload options are specified.
Two models of ball screw jacks are described: Model A (travelling screw) and Model B (travelling nut), with accessories like protective tubes, safety nuts, and limit switches.
Due to high efficiency, static or dynamic self-locking cannot be ensured without a brake motor. Guidance on self-locking and back-driving conditions is provided.
Selection criteria include buckling resistance, with diagrams for different Euler cases. Buckling limits for push loads are emphasized.
Factors limiting rotating speed include screw length and ball material. Formulas for maximum allowed rotating speed are provided.
Guidelines emphasize considering static deflection in horizontally mounted screws and using a supporting system for alignment. Maximum rotating speed is determined by screw length and diameter.
Ball screw life is defined by revolutions before fatigue, calculated using dynamic load factors and shock factors.
Construction features of the MA BS Series Mod.A include materials for components like the ball screw, ball nut, worm, and wormwheel. Efficiency, load capacity, and service life are highlighted.
Specifications for MA BS Series Mod.A include load capacity, ball screw diameter, gear ratios, and stroke per input shaft revolution.
Tables show linear speed, torque, and power for different input speeds and loads, with instructions for linear interpolation.
Total efficiency is calculated by considering efficiencies of the ball screw, worm-wormwheel, and bearings and seals.
Detailed specifications for ball screw jacks with travelling screws, focusing on models like MA 10 BS Mod.A, MA 25 BS Mod.A, and MA 50 BS Mod.A.
Performance tables illustrate input speed and output parameters like linear speed, torque, and power for different load conditions.
Total efficiency is calculated considering ball screw efficiency, worm-wormwheel efficiency, and bearings and seals total efficiency.
Tables detail maximum input power and torque for different input speeds and ratios.
Static braking torque values are provided for maintaining load in a static position.
For loads lower than maximum, linear proportion calculations are recommended for braking torque.
Technical specifications and performance data for ball screw jacks with travelling screws, focusing on models MA 200 BS, MA 350 BS, and others.
- Braking Torque: Static braking torque is calculated for maximum loads with specific ratios.
- Performance Data: Tables provide linear speed, torque, and power for various input speeds and loads.
- Efficiency: Total efficiency is calculated considering ball screw efficiency, worm-wormwheel efficiency, and bearings and seals efficiency.
- Max Input Power and Torque: Maximum input power and torque are provided for different input speeds and ratios.
- Life graphs are provided for constant applied loads with a reliability of 90%.
- Braking Torque Tables: Show static braking torques for different models and loads.
- Performance Tables: Detail linear speed, torque, and power for various loads and input speeds.
- Efficiency Tables: Provide efficiency values for different input speeds and ratios.
- Life Graphs: Illustrate the life expectancy of ball screws under specific conditions.
- Worm Wheel Rotation Detector: Verifies worm wheel rotation using a phonic wheel and proximity switches.
- Safety Nut: Prevents load dropping in case of main nut failure.
- Rotary Encoders: Available in Hall-effect and Optical types, with different resolutions and protections.
- Includes specifications like screw jack size, ball screw dimensions, worm gear ratio, and accessories.
- MA Series Mod.B: Features include a ball screw in quenched and tempered alloy steel and a lifelong synthetic oil lubricated worm gearbox.
- SJ Series Mod.B: Similar to MA Series but includes a grease-lubricated worm gearbox.
- HS Series: Includes a solid input shaft and lifelong grease-lubricated bevel gear and bearings.
- Standard matching options for ball screw and gearbox, with custom combinations available.
- Tables provide maximum input power and torque for different series and speeds.
Detailed specifications and performance data for ball screw jacks with travelling nuts, focusing on diameters and accuracy grades.
Life expectancy for diameters ranging from 20 to 140 mm, with accuracy grades IT 3, IT 5, and IT 7.
Theoretical efficiency of ball screws, constant despite speed and load variations.
Efficiency data for worm gears across various ratios and input speeds.
Necessary braking torque to maintain a static load on the screw jack.
Detailed data on load capacities, life expectancy, and efficiency for different ball screw configurations.
Specifications for components and systems, including rotary encoders and ball screw jacks.
Details on ball screw jacks with travelling nut (Mod.B) for MA BS and SJ BS series.
Guidelines for installation, maintenance, and lubrication of screw jacks.
Each screw jack is identified with a nameplate containing product code and other details.
Descriptions of various lifting system configurations and support available from SERVOMECH.
Catalog excerpts
BALL SCREW JACKS Made In Italy products 100% Made in SERVOMECH SpA Via Calari, 1 • 40011 Anzola dell’Emilia (BO) • Italy • T. +39.051.6501711 • [email protected] BALL SCREW JACKS
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© Copyright SERVOMECH This catalogue contents are under publisher copyright and may not be reproduced unless permission is agreed. Every care has been taken to ensure the accuracy of the information contained in this catalogue, but no liability can be accepted for any errors or omissions. The data shown in this catalog are in any case indicative and do not constitute any commitment. SERVOMECH reserves the right, at any time, to make changes at its discretion without notice.
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2 / Ball screw jacks
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1 / PRODUCT DESCRIPTION Screw jacks transform a rotary motion of an electric, hydraulic or pneumatic motor or even a manual operation into a vertical linear lifting motion (push or pull) or into a horizontal positioning motion. Screw jacks can be installed as a single unit or in lifting systems with different layouts connected by transmission shafts, couplings and bevel gearboxes. Screw jacks enable the synchronized constant movement of lifting systems even with a not uniformly distributed load. Ball screw jacks combine the gear unit with a linear drive performed by a ball screw that, in comparison...
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PRODUCT DESCRIPTION /I 1.1 Product overview SERVOMECH ball screw jacks range consist of three main series: MA BS Series, SJ BS Series and HS Series. Each family is designed and developed to represent a series of sizes with an adequate reciprocal gauge, to allow an easier selection of the most suitable size in terms of performances and costs for each application. MA BS Series High efficiency screw jacks • Recommended for continuous operation, duty cycle up to 100% • Lifelong synthetic oil lubricated worm gear • High precision worm gearbox, reduced angular backlash • Gearbox housing shape for a...
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1 / PRODUCT DESCRIPTION 1.2 Materials and Components MA BS Series and SJ BS Series screw jacks Input drive with precision worm gearbox, high efficiency design, ZI involute profile, reduced angular backlash. Bronze wormwheel, hardened and ground steel wormshaft, with true involute worm thread and shaft ground. Monobloc housing designed for a more compact and robust shape, able to carry heavy loads and ensure a high precision level of machining. • Housing: casting in hardened and tempered aluminium alloy EN 1706 AC-Al Si10Mg-S-T6 casting in grey cast iron EN-GJL-250 (UNI EN 1561:2011) casting in...
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PRODUCT DESCRIPTION /1 1.3 Size overview Ball screw jacks 6 / Ball screw jacks
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1.4 Models and design Ball screw jacks are available in two different models: • travelling screw (Model A) • travelling nut (Model B) The ball nut is integral with the worm wheel. The linear motion is performed by the ball screw being driven by the nut through the screw jack housing, therefore there must be enough space on both screw jack sides. In operation, the screw does not rotate and its translation is possible only if the reacting torque is applied. Accessories: • protective tube • protective bellows • safety nut • various screw end attachments • limit switches • anti-turn device • stop...
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PRODUCT DESCRIPTION / 1 1.4 Models and design MA BS Series screw jacks are available in both models (Model A and Model B), while SJ BS Series and HS Series are available only with travelling nut (Model B). SERVOMECH screw jacks can operate in vertical, horizontal or inclined plane. Different input options are available, such as: • MA BS Series and SJ BS Series: single or double solid shaft, motor flange or motor flange with second input shaft. • HS Series: single solid shaft or flange and hollow shaft All screw jacks are available with flange + hollow shaft or bell housing + coupling for: • AC 3-phase...
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MOUNTING POSITION DOWNWARD (D)
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PRODUCT DESCRIPTION /1 1.6 HS Series - Models and Design KINEMATICS SCHEME Scheme 20 Bevel gear wheel on nut side Scheme 10 Bevel gear wheel on side opposite to nut solid shaft with key, standard diameter solid shaft with key, larger diameter flange and hollow shaft for IEC / servo motor 10 / Ball screw jacks
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ADDITIONAL OUTPUT SHAFT Screw jacks HS Series can be equipped with one or more additional output shafts. Available versions are: • S: solid shaft with key, standard diameter • R: solid shaft with key, larger diameter The shafts position refers to the main input shaft and is expressed by an angle with counter-clockwise positive direction and screw jack top view (ball nut side). S 180 or R 180 WARNING! The rotating speed of the additional output shaft is always the same as the input shaft rotating speed, independently from the screw jack ratio. * - not available with transmission ratio R1 MOUNTING...
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SIZING AND SELECTION / 2 2.1 Self-locking conditions A ball screw jack is in self-locking condition when: • a push or pull load applied on a not working screw jack does not cause the linear motion (static self-locking condition); • by stopping the motor power supply of a working screw jack with push or pull load, the motion stops (dynamic self-locking condition). Due to the high efficiency of ball screw jacks, it is not possible to ensure the static or dynamic self-locking condition without using a brake motor. According to the total direct efficiency value of the screw jack the following conditions...
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2 / SIZING AND SELECTION 2.2 Ball screw buckling Euler I: screw jack housing firmly fixed to the base - free travelling screw end screw jack housing firmly fixed to the base - free travelling nut Example: with a push load of 7 kN applied on a screw length of 1 000 mm, the right selection is a screw with nominal diameter 40 mm, mounted on a screw jack MA 50 BS or SJ 50 BS or HS 50. Euler I Safety factor: 4 Ball screw length L [m]
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SIZING AND SELECTION / 2 2.2 Ball screw buckling Euler II: screw jack housing and travelling screw end fixed to pivoting supports screw jack housing and travelling nut fixed to pivoting supports Example: with a push load of 8 kN applied on a screw length of 1 000 mm, the right selection is a screw with nominal diameter 32, mounted on a screw jack MA 25 BS or SJ 25 BS or HS 25. Euler II Safety factor: 4 Ball screw length L [m]
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