The hydraulic lift has been around for over a hundred years. From the first water hydraulics to the latest VVVF drives with supercapacitors (commonly referred to as Supercaps), hydraulic lift systems have seen many advances.
Advantages of hydraulic lift systems include their low cost and ease of installation, meaning that hydraulic lifts ruled the market in the 1980’s. They accounted for almost 80% of installations in the UK, and they are still considered an ideal choice for a large proportion of new lift installations.
Advantages of hydraulic lifts: for builders
The success of hydraulic lifts over traction was due in part to planning laws governing height restrictions.
With traction lifts, the motor room tended to be the highest point of the building.
Hydraulic lift motor rooms could be sited in a variety of locations, removing the restrictive ‘box’ on top of the building. The lower headroom requirement also meant the hydraulic lift could serve the top floor of the building and still keep within height restrictions. Builders loved them as the majority of the loads were taken into the pit floor, reducing building costs, and the motor room could be sited remotely to suit the architect’s building layout.
Traction vs hydraulic: technology changes
In terms of floor-levelling accuracy, the hydraulic lift was vastly superior to the single and two-speed traction drives that passengers were used to at the time.
There were limitations, however; travel heights above 25m were very rare and the maximum lift speed was, and still is, 1.0m/s.
Hydraulic lifts travelled down under gravity and, with most not being counterweighted, required larger motors with high running currents which generated heat, sometimes requiring additional oil cooling.
Energy efficient hydraulic technology
In the last ten years, hydraulic lift technology has come on in leaps and bounds.
The climate change debate has placed a greater emphasis on energy efficiency and, in response to this, the more energy efficient VVVF drive has increased in popularity since the late 1990s.
Recent introductions to the market are VVVF retrofit systems where the existing controller doesn’t need to be changed. This allows the customer to benefit from a very cost-effective, partial modernisation, whilst seeing energy consumption of the lift drop by up to 59%, oil heating reduced by up to 54% and noise levels dropped by up to 36%. This is the ideal solution where a lift is unreliable due to overheating and no suitable location for an oil cooler.
Advantages of hydraulic lifts: modernisation
Due to the exceptional longevity of hydraulic lifts, most of the lift jacks operating in a clean environment with good quality oil and a stable operating temperature should still be in good condition, even though they may be more than 30 years old.
The car and sling can be replaced or retained and the car relined as appropriate; however, if a car is relined, care must be taken to ensure that, where the original cylinder is retained, the minimum buckling factor of the cylinder is not compromised by any increase in weight of the empty car.
When it comes to improving existing lifts, clients expect reliability, improved ride quality, floor levelling accuracy, energy efficiency, low noise and, of course, value for money. A new modern hydraulic drive system will tick all the boxes.
To meet clients’ expectations, some building owners might be tempted to replace the complete lift with a traction MRL, but these are not without their limitations. With a traction MRL, the options are limited by the dimensions of the existing shaft and reduced headroom and pit depth can exclude traction MRLs altogether. If the client is insistent on the use of an MRL package, we can supply a super quiet VVVF power unit with a footprint of less than 400mm square.
Where customers require a full modernisation, two main components must be retained, usually this is the sling (car frame) and guides with the whole hydraulic drive and control system being renewed. It is possible to renew the sling, but one other major component must be retained which makes things much more difficult. For the vast majority of cases retaining the sling is the most cost-effective solution.
Hydratec is a completely independent company and will help to select the right equipment for your modernisation from the wide range of suppliers in the market.
Whether you want a cost-effective solution just to improve ride quality and reliability or are looking for the most energy efficient complete hydraulic system, we can help. If you would like to find out more about modernising your existing hydraulic lift please contact us.