Barrier choice
Radio range
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Gate Operational Limits Barrier choice Radio range |
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Gate motors may be specified for use on leaves of a size or weight. These measurements are to be taken as maximums not to be exceeded. Parameters are most often accumulative. If any one parameter becomes significant, other parameter limits must be down graded to comensate. For example, a 900kg sliding gate used on a BK1200 (1200kg max weight) is at 75% of its capacity. The maximum gate length must therefore be downgraded to 25% of it's maximum.
Sliding gates are barely affected by wind, but swing gates are very suscepable. Gates in areas prone to wind, such as between high buildings, or opening outwards onto a road, should be chosen for worst conditions. A gust of wind against the direction of a gate with a DC motor may be interpretted as an obstruction, and reverse the gate. Similarly sliding gates can be impeded by twigs on the track. If a gust of wind seems trivial, try holding one end of a washing line on a windy day.
Whilst a sliding gate's weight is significant to the force required to accelerate the gate, the wheel's rolling resistance could double the running force. There is no specification laid down for many such immeasurables, so we must assume that all components are suitably chosen and in 'as new' condition.
Consider also the human factor. The force exerted by someone shoving on a long gate leaf is similar to a gust of wind. The force exerted by an intruder might be treble. An electric lock relieves the force from the operator. Accidental knocks from a car bumper multiply the forces a hundred fold.
Single leaf swing gates may seem an economic starting point for gate automation, but may be costly in the long run. They are more prone to vehicle damage and forcing, so repairs are likely to exceed the additional initial costs. They will benefit greatly from electric locking or any additional mechanical protection. A separate pedestrian entrance may help. Sliding gates are intrisically resistant to forcing, which is why they are favoured in commercial applications.
We ask customers to consider specifications comparatively, not in absolute terms. We are always pleased to advise on the 'phone. Forces can be estimated, but the exact can only be measured after the gate has been installed. So always 'over rate' the motor and 'under estimate' the counter forces.
There are 5 frame sizes for rising arm barrriers, with arms from 2.5 to 12 metres maximum to choose from. Most ranges have arm options or accessories. With such an array of options, it is worth narrowing down the choice by examining the application demands.
The older ranges are painted in RAL2003 traffic orange. This quite suitable for commercial purposes where high visibility it is important. Remember the arm is generally only 900mm above ground, so may be missed by HGV drivers. The new G8000 series is a conservative grey with yellow trim, but at 1350mm tall, the cabinet is quite imposing.
A high duty cycle motor is necessary for heavy traffic throughput. Consider more than one operation per minute for at least a one hour period to be high duty. All G4000, G6000, and G8000 have 24Vdc high duty motors. Most industrial applications controlling heavy vehicles are medium or low duty.
The longer the arm, the slower the barrier arm should move. The tip speed represents the effort required to accelerate a balanced arm, and also the safety risk. Lifting times of 1 secod per metre arm length are a good benchmark. Car parks often require high speeds for fast transit or to prevent tailgating. Arms as short as 2m are perfectly acceptable on lanes with width restrictions, and maintain safe tip speeds.
If your priority is for high security, then a rising arm barrier is not the right product. Skirts reduce the likelyhood of pedestrians 'ducking under'. However skirts can only be used on slow speed (often long) arms, and cannot be combined with soft edges. Skirts also swing in the wind and are likely to interfere with safety photobeams. The inherent dangers of poor safety with skirted barriers make a secure barrier a paradox without an armed guard!
Arm barriers are only susceptable to vandals when lowered. Tremendous leverage can be applied to the barrier's internal mechanism from the tip end of the arm. A floor mounted tip support is essential. One can specify a locking magnet to hold the arm down. Choose the highest practical frame size and round section arms for good mechanical strength. Avoid unnecessary accessories which will be broken off. Use DIR-Z phtobeams and the G8000 integral flashing light. Armed guards also work!
Radio transmission ranges are quoted as typical in best conditions. There are a number of factors to consider if you are experiencing shorter range than expected. The distance over which radio transmitters will work is dependant on four factors; radio transmitter strength, radio receiver sensitivity, ambient radio noise, and radio signal attenuation.
Radio transmitter power is a function of the square of the battery voltage, so a 10% drop in battery voltage may result in 19% power reduction. It is easy to compare transmitters if you have more than one. It would be better to replace the batteries, as wear and tear on a transmitter (dropping it) may slightly affect tuning.
Receiver sensitivity may be reduced if there is dampness within the control box, or on the antenna. It is unlikely that the a receiver would lose its tuning over time.
Antenna height improves reception by clearing low level radio wave absorbing materials. Top of the list is mesh fencing, railings, and of course metal gates! A car is essentially a metal box with gaps. Opening the window will not help, but holding the transmitter outside the envelope of the car body will. Buildings are peppered with metal objects that aborb radio waves to a lesser extent.
Radio noise is all the other 'chatter' from transmitters operation at the same frequency. Control devices are coded so that receivers only respond to their transmitter device. A radio door bell, for example, will not operate the gate. However if the door bell is transmitting, the gate can't 'hear' its own transmitter above the door bell chatter.
It is possible to move to a different frequency if you are experiencing particularly bad radio interference from other devices. The radio transmitters and receivers will need changing. Changing the switches or re-programming the transmitter alters the code only, not the frequency, in other words the message is changed not the medium.
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