In spite of all the apparent plus-points associated with electro-hydraulic gate systems, security installers are continuing to fit the electro-mechanical variety of perimeter protection solution. Why is that, and why are end users willing to accept it? Paul Dobson provides some timely answers.

Ten or so years ago the only places likely to boast automated gate perimeter protection systems were large, relatively high security sites operating within either the industrial or commercial sectors. Today, however, automated gates are in widespread use – even to the extent that they are regularly being fitted to individual homes. They are seen as highly desirable, providing enhanced security for the premises, its inhabitants and their possessions/vehicles. Above all, perhaps, automated gates offer peace of mind.

We have been supplying electro-hydraulic operators in the UK for 20 years, and have witnessed the growth in popularity of automated gates among the end user community at first hand. That said, we still come up against the same issues relating to quality, cost and ‘appropriate’ usage when clients are looking to choose electro-hydraulic or electro-mechanically operated gates.

When you consider all of the plus-points in favour of electro-hydraulic operators, why is it that installers continue to fit their counterpart systems? More to the point, why are end users accepting this without question? We firmly believe the answer lies with peoples’ perception of price, in tandem with the suitability of hydraulic set-ups.

A question of cost?

Certainly, electro-mechanical systems shipped-in from the Far East are cheaper than electro-hydraulic ones, but then some of them are cheaper than your average hairdryer? OK. That may well be a bit of an exaggeration, but you know what I mean! These systems simply aren’t up to the job at hand. Not by a long way. They should never be considered for any installation.

What about the sturdier, better-manufactured electro-mechanical operators? Well, you’d be surprised at the cost difference between these and hydraulic systems. You would be surprised because there is virtually no difference at all. We’re not talking long term costs, either. The actual cost of purchasing and installing an electro-hydraulic operator is virtually the same as that of an electro-mechanical operator. That being the case, price should never be an issue when it comes to deciding between the two types of system. If your installer tells you this then they are displaying a clear lack of understanding and market knowledge.

Is it not the case that hydraulic systems are really meant solely for use at top end industrial and commercial sites? Actually, they’re not. It is of major concern that end users are not being given the best deal in terms of reliability, durability and – most important of all – longer term cost-effectiveness.

With this in mind, let’s review how the two systems operate, and compare them for value.

Wear and tear problems

Both surface-mounted and underground electro-mechanical systems are based on a motor that drives a gearbox coupled mechanically to the gate either by lever or by rotating a threaded shaft. A nut is attached to the shaft that drives the gates open and closed. A simple principle, then, and one that works well. It just doesn’t work that efficiently in comparison with an hydraulic system.

The basic problem lies in the innate weakness of the drive gear, which leads to wear and tear of the moving parts and causes system failure much quicker than would be the case with an hydraulic unit. With the latter, motors drive a small lobe pump which pumps the oil back and forth, thereby moving the piston attached to the gate. The advantage here is that it is – generally speaking – only the piston seals that suffer any kind of wear, and not for some considerable time.

Perimeter security installation specialist Domsat has experienced the problems associated with wear and tear time and again, as managing director Robert Lane explains.

“The trouble with mechanical systems is wear and backlash in the gears, which leads on to very real problems in the motion of any gates on site,” suggests Lane. “Hydraulic systems simply don’t suffer from this. Some hydraulic systems that we’ve installed have now been operating for over ten years without any apparent wear and tear. We just top up the fluid from time to time, that’s all.”

Lane continues: “In practice, I have visited sites to repair mechanical operators a number of times, and more often than not I have had to replace them with hydraulic systems. Mechanical operators are cheaper, in particular at the bottom end of the market with 24 V systems, but then the end user literally ends up with a system that’s operated by a lorry windscreen motor! I’m not joking, either. I’ve taken some of these systems apart with my own hands.

“The client will be lucky if they last two years. Most pack up after 14 months, just outside of the warranty period. Even the better mechanical systems still have a finite motor and gear life. The end user must build this into the lifetime cost of the system to determine a real picture of value for money.”

When it comes to the range of operators now available, and the scope of applications they cover, electro-hydraulic options win hands down. This is possibly where end users have determined their perception that they are only meant for high security, heavy use industrial and commercial sites. The demands at such locations necessitate that operators have to be very sturdy, more powerful and highly reliable. As a result, they are often overlooked or seen as ‘overkill’ by security managers working on medium and smaller-sized sites.

Due to the operation of electro-mechanical systems, they are only really suited to low use environments (for example single residential dwellings, where the gates will not be opened that often in comparison with a business site).

Hydraulic systems also offer options such as hydraulic locking and braking. The former does away with the need for an additional lock, while in practice braking will slow down the gate in the last few degrees of opening and closing – therefore minimising the clatter of gate(s) with their stop(s).

Given that electro-mechanical systems are direct drive, it is not possible to mount those drives remotely. On those occasions where an underground operator is required, but where the ground is often waterlogged, remote options are available. As far as the installation of the two systems is concerned, they are virtually the same. Both systems generally comprise the operators, control board, access and safety equipment and fixings. The only area in which the two differ concerns fixings.

Electro-mechanical systems tend to be supplied with a universal bracket. For an hydraulic system the positioning of the brackets needs to be more precise. Thus standard brackets are supplied, for which your installer may require access to welding equipment. Stops for permanently fixed gates are also needed in the open and closed positions. Installation time can be slightly longer than with an electro-mechanical system, a point which end users ought to bear in mind.

Operation and maintenance

When deciding on the kind of gate system they’d like for their site(s), security managers need to be aware of certain quality-related issues. Hydraulic systems are much quieter as the pump is mounted in an oil bath. Electro-mechanical operators, on the other hand, generate more noise through the gears and threaded shaft which can be a real problem when they are close to – or actually on – the building fabric. The noise from mechanical systems will also worsen with time due to the wear and tear that takes place.

Normally, hydraulic systems are also smoother throughout their operating life, causing less vibration and strain on the actual gates. There is also a safety benefit to electro-hydraulic systems that many people aren’t fully aware of. Electro-hydraulic systems employ a pressure relief valve system such that if the gate is restricted in its operation, the oil will simply recycle and not crush any obstructions.

The current sensing that mechanical systems use stalls the current, which is sensed and switched off at the Control Board. However, this is less sensitive and much slower in its operation. Over time, this could have an adverse effect on the motor. This is not the case with hydraulics as the recycled oil provides a cushioning effect.

Maintenance is also an important consideration. Electro-hydraulic systems are virtually maintenance-free, as they are oil-filled either prior to or during installation. As the oil is only moved around within the system, it should rarely need topping up. The wear and tear aspect of mechanical systems will require regular inspections of linkages and drive mechanisms. The gate hinges should be greased, and gate alignment must be checked regularly on both systems.

Varying degrees of quality

So far, we have identified some of the real benefits to be had from electro-hydraulic systems. However, end users embroiled in procurement procedures should be aware that there are varying degrees of quality among this type of system. The major elements to consider here are the oil used, the couplings and the quality of the motor.

In practice, the latter can vary enormously. Some are supplied complete with a thermal cut-out feature. In principle, this sounds a good idea as it stops the gate if the motor becomes too hot – but then why would this feature be needed if the system was designed correctly and the motor was a quality product?

When this feature interrupts the supply, giving the motor a chance to cool down, the gates will stop where they are... Thus, the situation could arise whereby the gates are open and so causing a security risk – or they’re closed, creating road chaos as a result of people trying to use the entrance.

Of course, it’s not just gates that are operated by electro-mechanical and electro-hydraulic systems. Rising bollards can also be used. Bollards are heavy, and need the power of electro-hydraulic operators to operate them quickly and reliably. Barriers also benefit from the use of hydraulics, particularly with an air-cooled pump which allows units to operate under heavy use conditions (for example in industrial and commercial site car parks).

Bearing in mind all of the positive aspects for electro-hydraulic systems – cost-effectiveness, reliability, flexibility and durability – how can such solutions ever be seen as ‘overkill’? Fittingly, the last words on the matter go to Robert Lane.

“More and more end users are realising that they get what they pay for. They want a good, effective gate system that is totally reliable,” comments Lane. “Customers don’t want to be inconvenienced by their chosen perimeter protection regime, and neither do they desire pricey maintenance contracts. As far as the installers are concerned, we do not want to be called back to site on repeated occasions.”

Domsat has been in the business of installing automated gates for the past 15 years. Apparently, experience has taught them that mechanical systems are simply too unreliable. They only use hydraulic systems now. Nonetheless, it is up to individual end users to judge the evidence for themselves.

Gate system selection: what are the general considerations?

Gate Automation, Bollards and Barriers are availabel to cope with varying amounts of use, writes Brian Sims. Those systems with self-contained pumps/motors require a ‘cool down’ period. In heavy use applications, or at sites where there are busy periods, air-cooled units may be required. Make sure that your choice will be able to service the level of use required.

Whichever system you select, it will be expected to perform throughout the year in all weather conditions. If the entrance to your premises is in an exposed area, high winds could affect the operation of the gate automation unless this is a known factor at the time the system is designed.
Select the correct type of system for the immediate area. A barrier next to a busy night club, for example, could be a target for ‘drunken gymnastic displays’. A heavy-duty bollard would be more appropriate and less prone to vandalism and damage. End users should also consider the way in which vehicles use the site entrance(s), and where the restriction(s) ought to be located. A single entrance is more likely to have opposing traffic flow and possible tailbacks. If the restriction is too close to a busy road, any backed-up traffic could cause an accident.

In some instances, traffic lights are a requirement (particularly when bollards are installed in busy or tight situations). The vehicle bonnet could obscure the view of the bollard the closer the vehicle gets. Use of the same entrance for both pedestrians and vehicles should be avoided. Where possible, allow for a separate entrance or at least a kerbed pathway.

Some of the areas you should consider when thinking about a system are: What is the level of security you require? What is your primary reason for having a system? What materials do you want the gate made out of? Do you have a view on the style and design which will work best, etc

Source

SMT

Postscript

Paul Dobson is sales director at BPT Automation, a division of BPT Security Systems (UK) (www.bpt.co.uk).

Next month: Security Management Today reviews www.guidetogates.com, an excellent new web site dedicated to end users who are looking to design and specify perimeter protection regimes.