Category Archives: Door

Replacing a Linear Actuator

So, you may remember that I removed a section of the bar that opens the manual door and replaced it with a linear actuator, which was then attached to a remote unit that meant that the door could be opened and closed by the use of a remote fob.  And the system worked really nicely for a couple of years.

The broken back plate from the Firgelli 8-12-12 actuator.
The broken back plate from the Firgelli 8-12-12 actuator.

Unfortunately, it was subjected to stresses that I hadn’t foreseen.  While I had looked at the 300 lb holding ability, and the 8 lb press (not 150, I came to find out – a labeling error) power as sufficient, I hadn’t prepared for a teenager who was trying to pull closed the accordion door while the hand-control was locked closed.  The back plate of the actuator snapped under the stress.

Faced with this situation, I obviously had to fix this, so that the door could be closed and secured, but still usable.  As a temporary solution, I had a piece of 2×10 that just fit in the bottom stair that would block the door from opening, and I could still climb in and out of the rear door which has the deadbolt lock.  I then set about trying to find a replacement plate.

The new end case for the ill-fated actuator.
The new end case for the ill-fated actuator.

Firgelli Automations no longer made the model that I had purchased, so had no parts for it available.  I then attempted to fab up a ‘sheath’ to enclose the back and secure the engine/shaft casing.  As I was finishing this up, the engine finally failed, which was very frustrating.  As I did some research, I found that many of this model had had the engine fail, and it was a usual end-of-life situation for it.

While this was disheartening, I contacted Firgelli’s support about getting specs on the engine to see if I could find a replacement somewhere, but no luck.  They make all their components themselves, so it was a special run.  They were able to point me toward a different model that was more rugged and had a more powerful (and durable) engine than the model I had.

Firgelli Mini Linear Actuator 15lbs Force – 12 Inch Stroke


List Price: $139.99 USD
New From: $139.99 USD In Stock
Used from: Out of Stock

The new actuator in place.
The new actuator in place.

This model is much more rugged than the original unit, and about twice as powerful.  And the connectors are an eighth of an inch bigger in diameter than the original, which meant that not only did I have to undo all my sheathing welding, but I had to fabricate new sockets too.  As we were right near the limit of when the inspection for the bus would run out, they’re, unfortunately, rough and unpainted.

New arm socket (note removal of stop-nut from threaded end).
New arm socket (note removal of stop-nut from threaded end).
The new handle-end socket. (Well, okay, to be fair it still has some old paint on it).
The new handle-end socket. (Well, okay, to be fair it still has some old paint on it).

It’s also an inch longer when fully retracted, and I was able to compensate for about 1/2 an inch with the adjustment threads at the door, but it means that the door doesn’t open quite as wide as the old unit allowed – but that’s just me being picky.  (It’s also cheaper to buy directly from the company’s site than through Amazon …)

While I’ve not got to painting the new unit, I do have to admit that the works are much smoother than the old unit. Check it out in action:

I let the magic smoke out of a wire *or* the Magic Door (Linear Actuator, Part 2)

So you might remember that when I put in the linear actuator for the door it had a handy remote that could easily both open and close the door.  Now, as much as the remote controller unit was a black box, its exterior functions were really simple – the two wires for one channel either are pos/neg to open or neg/pos to close, thus sending the 12 VDC through the linear actuator’s motor one way or the other to get the desired result.

And, in understanding that, I had thought that I could just put a DTDP switch in place and be able to electronically open and close the door with the switch.  My thought was that I would use the positive power and ground that the controller was hooked to, and that way, the circuit would connect in parallel to the linear actuator’s wires, but bypass the controller entirely, and all would be good.

It was easy enough to hook up, and after double checking the circuit, I tested it.  The door was closed, and I flipped the switch, and the actuator whirred and the door opened, leaving me happy, until I flipped the switch back and as the door started to close, one of the wires from the controller to the linear actuator let out all its magic smoke as the insulation melted away.  I quickly flipped the switch off and examined the system.  All was as it should have been, the polarity to the linear actuator just being put to the opposite wires.

A quick check on the remote showed that the controller unit was still clicking along with the use of the remote’s buttons, but the wire was fried, and the linear actuator wasn’t working.  As I needed to clean up the bus to move it, I quickly disconnected the switch, cut out the damaged wire and spliced the ends.  The controller clicked but again the actuator didn’t twitch.

I tested the actuator wires by making a circuit to the positive and ground, and the actuator slide the door closed, much to my relief.  And then I decided to test out the second channel of the remote.  I quickly wired it to the actuator (with no additional switch in the circuit), and tested it out with the remote.  Again to my relief, the door opened, and then closed again with the remote.  So the system worked, and I buttoned it all up.

So now I’m left with a DTDP switch, which I think may end up running some lights, a controller board that (I discovered after the fact) needs a new wire soldered to it so the first channel will be usable again, and a quandary about why one wire of the controller shorted the circuit while the other didn’t.  But, the door still works with the remote, which is the important part.

A Linear Actuator *or* The Magic Door!

Being that things warmed up and I was trying to get some stuff put away in my shop, I decided to tackle the linear actuator and get it in place.

The linear actuator, extended.
The linear actuator, extended.

Now some of you may be pausing (or going to the search engine of your choice) and asking ‘what the heck IS a linear actuator?’  Well, it is a screw/worm gear drive that pushes/pulls a shaft along a straight line, into and out of the housing.  These are the things that move lots of slide-outs on modern RVs and trailers.

But, you might also ask, if you don’t have a slide-out, why would you need a linear actuator?  Well, one of the problems with our bus, when we got it, was that there was no way to lock it.  The emergency doors had handles, but they had no key-locks though, they could be locked with a padlock on the interior handle or by installing a keyed household deadbolt through the door to interfere with the existent deadbolt inside, which is what we did to the back door.   The front door locked like a dream, as it was one of the swing-lever accordion doors.

The front door, with the swing-latch in the closed and locked position.
The front door, with the swing-latch in the closed and locked position.

As you can see, this is really secure.  Even if someone broke the glass to get in, they’d have to reach up and unlatch the handle by the gear shift in order to swing the door in.  You might also note the cloth by the latch – one of the problems with the door is that the latch has worn and it rattles while you drive.

The swing arm in the open position.
The swing arm in the open position.

Anyhow, you might note the long rod that connects the swing arm in the center to the door.   When the swing arm is moved to open the door, the rod gets pulled in and pulls the door accordingly.  In looking at it in the right way, if the swing arm was a static unit, in order for the door to open, the bar would have to shrink, optimally about 13″ to open the front door fully.  It just so worked out that Firgelli Automations sold not only a linear actuator with the motor integral to the unit (rather than mounted alongside), but also a remote kit.

Firgelli 12 Inch Stroke Sleek Rod Linear Actuator – 150 lbs Force


List Price: Price Not Listed
New From: 0 Out of Stock
Used from: Out of Stock

4 Channel Remote Control Systems


List Price: $79.99 USD
New From: $79.99 USD In Stock
Used from: Out of Stock

Now, I chose the higher-powered 12″ model rather than the 14″ one, as I didn’t want to stress the door by pushing it too far, and the bar just wasn’t long enough to take the length of the fully opened 14″ one.  But the high-powered one has a push/pull strength of 150#, and a stopped strength of 300#, which seemed pretty strong as a replacement for the 5/8″ steel bar.

Threaded bar end and the hinge at the door.
Threaded bar end and the hinge at the door.

In looking to replace the bar, I needed to save the threaded end that attached to the hinge at the door, and the collar end that attached to the swing-arm.  These were easily enough cut away with the angle-grinder, and leveled (as best I could).

This is a picture of my 12" linear actuator, open, against the cut bar.
This is a picture of my 12″ linear actuator, open, against the cut bar.

I laid these out against the actuator and things looked pretty good.  But where I had planned to weld right to the actuator, it turned out that the fittings on the actuator were aluminum, so I had to create some pockets of angle-iron that would be the way to attach it.

Parts of angle iron for the connector pockets.
Parts of angle iron for the connector pockets.

These had to be cut down, welded, ground a bit more, welded again, then ended with some flat plate and drilled so that they would attach to the actuator.  As the bar-end of the actuator was not a nice, square piece but rounded as the bar was, and then rounded to allow for a swiveling action that I really didn’t want,  I had to make the pocket that would connect to the threaded rod not only a tight fit, but also longer so that it wouldn’t swivel or flex at all.

The connector cups, fitted and drilled to be attached to the actuator.
The connector cups, fitted and drilled to be attached to the actuator.

So after a little extra work, I had everithing ready to put together.  The connector pockets needed to be painted to keep down rust on the new grinds, and I decided to go with the brass paint, for the fun of it.

Here's the new linear actuator in place!
Here’s the new linear actuator in place!

The linear actuator bar wend in place great, however I discovered that if the round, extendable actuator bar with the screws on it moves and allows you to screw it into the door fitting, you’re actually unscrewing it from the motor and it’s a bad thing ™.  Luckily, the bar screwed right back into the actuator, and all I had to do was detach the other end from the swing arm and then screw the whole bar in and it worked out fine.

The remote, inside the door switch area.  The wires for the linear actuator go out through an existing hole in the bottom.
The remote, inside the door switch area. The wires for the linear actuator go out through an existing hole in the bottom.

I decided to use the space inside the door switch area of the swing arm to mount the remote, which worked well, as it already had a power line and ground screw in place.  The best thing about this placement is that the wires from the actuator don’t hang up on the swing arm when I use that.  With the actuator fully extended, the door operates normally.  With the swing arm locked, it works like this:

True it doesn’t open quite all the way, but it’s enough to get into and out of the bus, and the full extension of the linear actuator closes the door up snug enough that the door handle doesn’t chatter because it’s loose and worn anymore.

Now, all I need to do is get a DPDT swtich to run the door from inside, and it will be perfect.  But for right now, I have a keychain remote door lock for the bus!