no lock?

Are you talking garage door? If so, nor does mine. It relies on it not being possible to raise it other than by coiling it back up onto its axle, either electrically using the remote controller or with the hand crank inside the garage if the electrics should fail. I asked about security before I had it installed, and the guy said it was very secure (BHWSTWH).

Jim GM4DHJ ... submitted this idea :

If you mean shutter on a door, you should find that as it closes, the barrel should continue a little further than needed to actually close. Hinged plastic link sections connecting door to barrel, then are partially inverted, so as to jam or lock the door down. My 2m wide door has four of these plastic hinges, spaced along its width.

The only way the door can be then lifted, is by turning the barrel, or by forcing the door and breaking the plastic hinges.

Out of curiosity - what happens if you're not in the garage, the power fails with the door closed, and you have no other entrance into the garage?

My garage door specifies there must be an alternative entry point.

Judging by the keys for a couple of up and over garage doors I've encountered the locks fitted to many garage doors are of the low quality, low security type.

How about just a lock that prevents the winder being used?

SteveW

Fortunately, there is an entrance through the house, via a heavy and fairly secure fire door.

That happened to my neighbour. Burglars attempted to sabotage the gates (don't ask me how that would help them) and managed to kill the power to the garage. The consumer units etc were in the garage. We had to destroy the door.

Bill

From my own sample of 7 garages in my lifetime of property residence.

A grand total of zero had such access

so pretty much a deal breaking restriction IMHO

tim

on 06/06/2019, Davidm supposed :

If the door roll is on the inside, they offer a linkage down and through an access hole for a manual winder. If the roll is mounted outside, or there is alternate access, you can just hook an handle on to the end of the drive for the roll.

Its probably using a worm drive which of course cannot be operated backwards, so to speak. Brian

alan_m was thinking very hard :

Yes, just a simple flat key, probably easy to pick.

The roller doors are a little better, but difficult to make anything proof against a determined attack. All you can do is ensure a lot of noise is involved in breaking in and getting through a roller shutter woud be a very noisy exercise..

As long as you remember to unlock it before operating it or it might self destruct!

Brian

They use a multi section planetary gear, to reduce the motor speed right down. You cannot force the barrel around, that part is very secure. The only way is to force the door up against the over centre plastic links, breaking them whilst also lifting a quite heavy door.

They do self destruct - there is a deliberate weakened section in the drive shaft from the motor. Overload the drive and the shaft snaps, as I found. The attachment on the door in the Crocodile ad., is I think a wireless obstruction detector. If the door tries to close onto an object which makes contact with the edge rubber, the door stops and reverse. I added a IR beam system across my door. If the beam is broken by an object, 'down' button does nothing, or if it is broken when the door is going down, it reverses and goes back up. I added a remote LED indicator to mine, so light comes on when the car is just clear of the door aperture.

Simple. All of these doors have a simpe way of disconnecting the gearbox and then the door can be rolled up by hand

Not really any different to any (garage) door where the lock fails, save you just have to wait for the power cut to end rather than get more creative. Having helped several neighbours over the years with garage door issues, waiting for a power cut to end could be the better option.

We have a secondary door so it isn?t an issue but it was something I thought of. The roller doors are quite hard to wind up by hand, at least the double ones. Trying to (somehow) push one up so it winds must be all but impossible. You could smash it open but that is true of any almost door.

At least some (if not all) have a winding mechanism accessible from outside if there is no seconary door.

Used in insulated roller garage doors when there is no other door allowing access to the garage. This involves feeding the internal manual override system to the outside of the garage through its brick wall. A steel plate is fitted over an access point and this plate is lockable. When unlocked, the winding handle can be fed in through the access point and be used to wind the door up or down until the power comes back on.

External winding handle access point (high Level)

For roller garage doors that are fitted externally, with the manual override being accessed from the outside. This type of mechanism also has an access point covered by a lockable steel plate which can be unlocked to gain access to the inside and wind up or wind down the curtain.

Brian Reay pretended :

Mine is not difficult to manually crank, it is very low geared and needs lots of turns to raise it.

The control system is DC 24v, the motor 240v. My plan for if the 24v system fails, is to just power the motor directly off 240v, it internal motor limits will still be in circuit.