Gates

[Oxo]

Just change the PCB on the controller for a soft touch reverse operation without beams or stops.

I would describe it more technically but you would only cream it to death.

 

Your idea is still flawed.

 

End of.

 

Put a leading edge on the stop end, not the gate if you find it too difficult to use a loop.

 

And your still wrong.

[arfur mo]

bit of a shame not saying why you say flawed? how is discussing creaming anything?

tbh i was a but shocked this gate did not auto reverse, they have had the same issues as James with broken kit.

It is a FAAC controller, but no idea which model.

Today i was shown the installer had used some 4" square metal section that was now loose, it is either side for the mounting bolts, this has broken on one seem, but they have not been back to fix it, so it now vibrates like buggery when used.

imho they should have used 'H' girder, i wonder in your opinion would it be better if the motor housing was mounted on hard rubber blocks to help absorb the shocks?

[Oxo]

I`m not going to repeat myself.

Because you do.

It does not have to, latter ones will if of course used.

See above.

So, they use what they use.

Why "H" section? How many you fitted?

Hard Rubber blocks would crack IMO.

[arfur mo]

I`m not going to repeat myself.

Because you do.

It does not have to, latter ones will if of course used.

See above.

So, they use what they use.

Why "H" section? How many you fitted?

Hard Rubber blocks would crack IMO.

Me, doing heavy work? that would be to much like getting a proper job! but i'd guess the gate fitters have done plenty - so not much of a recommendation is it?

i was thinking of the hard rubber like those bump blocks on back of heavy trailers, but not as thick, or it would be too flexible.

this gate i'd guess weighs around a ton, if not more. the walls of that mild steel square section are fairly thin and it's simply open, just welding end caps on would have been an easy job to strengthen it, and likely have prevented the split in the first place.

[james.wilson]

The problem with flexible mounts would cause excessive wear on the drive gear, ie when starting and stopping it would force the rack and pinion further away from each other at their highest stress moments. Clutch on drive gear rather than motor would be better but would allow the gate to be forced. Motor braking like i used to use when i was little in model car racing seems one option. Id say pulsing an ac motor would stress it more

[arfur mo]

the ideas would need tweaking, OXO has recommended a box from his no argument superior experiences, so best go with it.

i don't claim any formal qualifications, other than passing a written and practical exam to get Grade 2 on Chubbs, and my national cycling proficiency test (got 96% despite flattening 2 instructors .

using that 'box' theory, take one half of the ac cycle it rises from zero through to full voltage and back to zero. if you run a motor at stall it will get very hot very quickly, so using that full cycle you are running your motor from stop,effectively through stall for say 50% of that cycle, and again as the voltage decreases.

the motor is designed to disperse that heat from that abuse, but then you gate due to grit, alignment, heat etc can get harder to operate, so the motor is now stalled more than when everything was new, that stalling is resistance transferred through the gears etc.

by using only the top of the cycles, your not causing heat built up by stalling the motor.

[james.wilson]

Are you talking high freq 3 phase motors now? If not you are going square wave?

[Oxo]

Sorry I got this reopened.

[Cubit]

Sorry I got this reopened.

So you should be.

[arfur mo]

Are you talking high freq 3 phase motors now? If not you are going square wave?

no, just standard motors as used on conveyor belts and general usage.

it's not frequency control but mark space, using only the upper part of the cycle.

@ 50hz when you apply the power the motor is idle, that will cause initial low voltage high current inrush current and so heat very quickly, the motor has to overcome the inertia of driving the equipment attached to full motor speed, extending inrush time and causing more heat.

might not be the best example, but easiest to get the theory over

take a 12 vdc mag lock, use a variable output bench PSU. step the voltage up from zero very slowly with the plate attached or slightly away to max the flux, on the PSU meter you will see the current drawn is much higher against when using 12 volts, it will get a lot hotter than when run at near 12 volts,. i have seen them destroyed by engineers leaving a 7 amp battery to hold the door shut that has slowly gone flat, and burned the coil out.

i know the question will be asked 'how about when the mains fails'.

psu won't supply more than 3amps, 1 amp in most cases before a fuse blows.but direct off a battery depending in cable length a near flat 7 amp can supply a lot of current and there is no fuse in the way.

back to our motor.

by removing the lower voltage part of the mains cycle you reduce inrush at low speeds, also current taken during operational parts of the sign wave because the voltage us there to drive the current.

perhaps a more practical way to look at it,

say you have a door that is reasonably stiff. lean or push hard on it don't move it much and you build up a sweat persisting (low voltage part if cycle), know barge it likely that opens it far easier and moves the door a lot further, quicker for far less effort and sweating than pushing (high voltage part if cycle).