Once again we are singing the praises of a range of products we supply in significant numbers to our customers; we have discussed electrical cylinder actuators and the push/pull linear chain recently – but there are a great many occasions when a simple and reliable screw jack is the right component for your application. Let’s look at what a screw jack is, and why it could be precisely what you need.
Screw Jacks are a modern adaption of a technology which has been around – and been successfully implemented – for thousands of years. In essence they are a load-lifting device which can handle significant weights with minimal force applied, a travelling screw either driving the load or the load itself travelling along the screw to manoeuvre a load. The new advances which have increased the efficiency of this technology are electric geared motors (though pneumatic and hydraulic motor options are available) and ball screws; whichever version of screw jacks you select, the lifting capabilities of can be utilised in applications for small loads of just a few kg up to 200 tonnes.
As a reliable, controlled method of linear motion, screw jacks have long been relied upon – and they still provide an affordable solution for a wide range of applications.
One of the benefits of screw jacks is that the load is generally self-locking; this means that the motion can’t be back-driven by the weight of the load. This makes them a very safe option, and the load will maintain that position even when the motion force is removed, no matter what load the screw jack is supporting. This might not be the case with a ball screw, but they have their own benefits.
Compared to hydraulics – which is the most commonly used competing technology for lifting high loads – an electric motor powered screw jack is considerably more energy efficient. Whereas hydraulic systems need to maintain a constant pressure, circulating the fluid at all times to maintain a position, the screw jack motor is only required in the process of driving that load – which is then held without the need for power.
The technology can be utilised in a wide range of environments, from industrial plant processing to lifting stage platforms in the theatre, and this adaptability keeps these deceptively simple components high in popularity, so trusted and reliable are they as a device for lifting and controlling loads – particularly for environments where workplace health and safety legislation so significantly drive the development of managing significant loads.
Screw Jacks are inherently safe and comply with a number of ISO EN standards for machinery, lifting tables and platforms. Some of the main safety features are:
Safety Nuts – Secondary slave nuts can allow the monitoring of wear and secondary redundancy if the load carrying nut fails in service. Sensors can be fitted to detect failure/max wear reached.
Self-Locking – The trapezoidal spindle combined with the worm gearbox results in static self-locking of the load when the power is removed.
Secondary Safety – For lift systems for personnel redundancy or secondary safety is required. Screw jacks can be offered with safety nuts, brake motors and even linear braking elements, which ensures that a secondary safety measure is always in place.
When you’re designing an application which needs to raise and lower a platform or load, on any scale, our range of screw jacks come in a huge variety of designs, sizes and functionalities – so explore our Screw Jack selection here, or call the office to speak to one of our technical sales engineers about the best solution for your project.