The merits or otherwise of hydraulic lifts versus traction lifts is something Architects, Engineers and Lift Companies debate from time to time. The following 'Debate' is offered to interested parties.

• Which equipment is better suited?
• Is there a cost advantage?

Hydraulic lift manufacturers often only see the advantages of their product and seem to turn a blind eye to the many disadvantages and perhaps many chapters can be written on each of the factors indicated below. However, to be pragmatic, buildings are not constructed solely for the lift engineer's benefit but are there to perform a function for a given occupier! With this in mind, response to hall calls and the ability to move a given load efficiently is the only factor.

Please see the relevant issues chart below.

Conclusion

To provide a 'win/win' situation for both Client and contractor, hydraulic lifts should only be applied in the correct application. Designers and contractors should be sensitive to a win/lose situation, i.e. where the Contractor on the one hand wins, having managed to sell the convenience of hydraulic equipment in terms of planning and application; and on the other, the Client loses throughout the life of a building where the building remains 'under lifted' as a consequence of poor performance or unreliability as a consequence of over use.

In our view, the following rule of thumb applies: If a traction lift can be easily accommodated within a building, then in the long term it would be beneficial to provide such an installation. However, there are many examples in low rise, low usage buildings where the provision of a hydraulic lift can undeniably prove to be the most suited.

It should be accepted that pound for pound traction lifts are more expensive for low speed/low duty applications. However, traction lifts are significantly cheaper than hydraulic lifts on higher speed/high duty applications, i.e. hydraulic lifts cannot be installed successfully for lifts over 1 m/sec.

Furthermore, hydraulic lift performance is dependant on the viscosity of the hydraulic oil, which requires heating when cold and cooling when hot - all very expensive in terms of energy consumption.

Relevant Issues	Advantage With:	Disadvantage With:
Carrying capacity per £	Hydraulic (within limitations)	Traction
Speed of car over 0.8 m/s	Traction	Hydraulic
Floor levelling accuracy	No advantage either way given modern technology
Headroom requirement	Hydraulic	Traction
Pit depth requirement	No advantage either way because minimum standards have to apply
Motor room location (flexibility thereof)	Hydraulic	Traction
Serving over 7 levels	Traction	Not achievable in practical terms
Serving under 4 levels	Hydraulic	Traction
General performance/starts per hour	Traction	Hydraulic
Odious Smells	None with traction	Hydraulic
Cost of low rise installation	Hydraulic	Traction
Cost of high rise installation	Traction	Hydraulic
Energy consumption costs	Traction	Hydraulic
Standard floor to floor performance	Traction (5-6 secs)	Hydraulic (9-11 secs)