PARAMETERS FOR SCREWJACK SELECTION PROCESS

The main features for screw jack-selection are:

• Load dynamics (load changes along stroke)

• Speed (linear speed along stroke)

• Duty cycle

• Environment/Ambient

• Stroke length

• Power supply

• output rpm (gear box)

• output torque (gear box

Screw-jacks are devices meant to be installed into larger machines therefore they cannot be considered as safety devices (see EC law CE 89/392 and further CE 91-368,93/44,93/68). They are not elements that shall discriminate, with their use or with their fault, safeguard of people’s safety and health. Thus it is not allowed to use MecVel products as safety devices.

Screw-jacksare independent systems used to obtain linear movements: basically, they are made up by an electric motor, rotating a lead screw directly or by means of a gearbox.

Load shall be axial only, but it can be tensile or pushing, no matter what push rod direction is. Screw-jacks can work both with or  without load. Type “T” features a lead screw going back and forth, while type “R” features a travelling nut and a rotating screw. Self-locking or not self-locking behaviour depend on the gearing ratio and load value. In any case, self-locking is always possible with additional components. According to type of screw jack and driving / control system used with it, we can have a simple ON / OFF  device (pushing and/or pulling) or a servo-mechanism. Scewjacks main advantages towards pneumatic and hydraulic ones are basically following: they can easily stop in intermediate positions all along their stroke, the power consumption happens only while the screw jack is working (not necessary to keep it in position for example), the power supply is clean and easy to find, with no need of tubes. Thus, wirings on applications frameworks will be easier to build and no fluids (i.e. oil) can accidentally be spared. This last feature is necessary in food and textile environments

INSTALLATION,USE,MAINTENANCE AND WASTE GUIDELINES

MecVel requirements:

• Screw-jacks being installed by qualified and authorised technicians.
• Electrical connections done by qualified personnel; during installation main electric power supply shall be turned off so to run safely all these operations (wearing also protection suits, gloves and glasses).
• Screw-jacks need very few maintenance operations: cleaning and eventually greasing (according to instruction manuals).
• Scheduled inspections to working screwjacks in order to detect in time possible problems: in case of doubts contact MecVel.
• If something wrong is detected do not try to fix it without MecVel’s technical advise: its after-sales dept. will be at your complete  disposal to solve it out.

All products are delivered with proper packing, according to customerneeds and goods dimensions / weight. We recommend a safe

product handling, using for example forklifts, safety belts…. ackage, as well as the Screw-jacks themselves, shall be disposed /

wasted according to laws in force in the user’s Country.