EZ type lock stopped locking!!

[tomcmo]

I drive a 2010 voyager from my powertec f50 and recently my EZ lock has worn and will not lock. I have had the EZ lock replaced but my confidence is shaken as I have been using EZ locks for almost 20 years and these ones seem to be unreliable after a few thousand miles of use. I'm weighty and I use a heavy powerchair that puts strain on the EZ lock but I'm struggling to accept that the slight wear (see pics) is responsible for the unreliabiliy issue. I am hoping that the wheelchairdriver legend BM and forum users my have experience of this issue or some idea of why my EZ lock is effected this way?

Any response appreciate, thanks

[Burgerman]

The amount of wear is negligible. The slight burr it causes can cause the easy lock moving parts to jam against the body of the device.

Take apart, carefully file all the burrs away, and lightly grease and reassemble.

If that doesn't fix it you have a bent, or seized part, faulty micro switch or something. Examine with a fine tooth comb.

[motoman]

The tiny amount of wear is not your problem. I was having issues with mine last month and took it in with burrs 10x worse than that. The guy thought the burrs were my issue but it turned out the problem was something else.

Is this a fairly new install? Does it have the secondary bracket installed with the extra (smaller) bolt to keep your chair straight??

[tomcmo]

Thanks for the replies.

Yes it does have the secondary guide point at the front of the chair and all is located correctly as far as I can see. As you say the wear is negligible and I have had it cleaned up and examined thoroughly and it still releases under force. Comparing it to my new one it looks exactly the same so it's a worrying mystery as to why it releases. I did about 20,000 miles in an identical clamp that had far worse wear on it.

[Burgerman]

They are very simple things. I made a stainless steel top plate for mine. It MUST be possible to see why it is releasing. It is all in front of you?

Unless its electrical. A quick power pulse and it will open. Or a latching spring missing or something.

[tomcmo]

Totally agree with you BM it should be obvious but we can't see anything wrong with it other than the minimal wear on the jaws which seems an unlikely candidate given the fact I have experienced more wear on identical locks that continue to work. Its definately not electrical as the fault occurs witout any power connected.

[Mark]

Could I suggest that you try to simulate the chair with similar bolt that is fastened to something (like a length of angle) so you can apply a reciprocating force to the ez-lock. Without the chair in the way you might be able to spot what is triggering the unlocking. You might be able to do this from alongside the car through an open driver's door.
Following BMs suggestion that it could be an electrical fault, disconnect the release solenoid, drive the vehicle around and see if you still get random unlocking. Then use the manual release to get out.

[Mark]

Another thought..... Could it be that it isn't fully locking in the first place?

[tomcmo]

It is fully locking as far as I can tell. I have uploaded a couple of YouTube vids simulating the EZ lock in use and a pic showing the EZ lock externally. We have tensioned springs and tried a variety of adjustments, cleaned the wear and the jaw surfaces, lubricated and reassembled and continue to have the same result.

http://youtu.be/kDZc9ZncGS4
http://youtu.be/NsYqJ-l3bas

[Burgerman]

AFTER LOOKING
The LARGE pivot bolt is in the wrong place. Any rearward loading will try to spring it open. Look at the following two pictures. I Edited one of them to put the pivot bolt in the correct place. On the centreline. NOT offset! Look carefully.

Looks like one of bekkers. But totally different to mine. Take it back and tell them its not designed correctly. Someone that doesent understand physics designed that, and its dangerous. A stronger spring will "appear" to fix it. But if you get hit from behind, or on a steep hill, it will release.

Fundamental design error. They will/should do a recall. Going to look at mine!

Photo 1 WRONG!!!

Image1.jpg (242.94 KiB) Viewed 10695 times

Photo 2 FIXED!!!

Image2.jpg (243.56 KiB) Viewed 10695 times

[motoman]

Well, if the pivot bolt is in the wrong place then every one on earth is wrong as the one in my van is nearly identical to the one in the pic and mine works. Kinda weird, but if mine is designed like this, i just lost my confidence in it.

[Burgerman]

If you don't believe me, then visualise that bolt even further to the side. Or mentally draw a line from bolt to the flat 90 degree sliding edge. That edge would need to be at about 5 degrees anti clockwise to give security.

That pivot bolt MUST be central, *(or the contact surfaces angled so that they are at 90 degrees to the pivot point at a tangent to an imaginary "circle").

One look at the videos will tell you I am correct. Saw the error as soon as I looked at it. Pretty obvious.

What's more, mine is the same. So I tested it hard. If I try, full power reverse chair, and parked on an uphill section of road I too can reverse out if I rock the chair! It pushes the spring out of the way as the geometry forces the latch to open.

Like this. http://www.youtube.com/watch?v=NsYqJ-l3 ... e=youtu.be

As usual, I will need to repair it properly myself because this is an accident waiting to happen.

For EG, at a busy junction. Waiting to turn onto a main road from a side road on an uphill slope. See gap, gun van, roll into the back and cannot steer or stop...

Why would they not see this? And its not just one manufacturer since they all copied the same error from each other!

[Lord Chatterley]

That video...

Unbelievable!

LC

[motoman]

Whats even worse is they are mounting these backwards (opening forward) in pick up trucks with conversions...a sure death trap. I lost my faith in mine now...

[rollingcowboy]

it will be interesting to see if EZ-Lock respond to this info.
those videos are stunning
is the solenoid supposed to be 'on' all the time when the pin is captured?
even with the pivot off center there would not be much force req'd to hold the arms closed.

[motoman]

is the solenoid supposed to be 'on' all the time when the pin is captured?
.

No, the only time the solenoid is energized is to open the latch.

[Burgerman]

is the solenoid supposed to be 'on' all the time when the pin is captured?

No its just a release. It is still / remains powered though until you reverse out. Then a micro-switch turns off power again.

even with the pivot off center there would not be much force req'd to hold the arms closed.

The Geometry is simply wrong. The greater the force the chair applies (say you get hit from behind, hard or whatever), the greater the force opening it against any spring fitted. A stronger spring will hold it close more securely, but push hard enough and it will release. That is simply not a safe design. Its a fundamental design error. A schoolboy one that any retarded engineer would spot. Who designs these things... Its like saying 'lean hard' on the car door un a turn, and it will spring undone... Not acceptable! It SHOULD be the reverse. It should hold harder under load.

There should NOT be any 'opening' force applied by the chair. Just a rearward one. The bolt needs to be central for this to be the case. These look like bekker devices so far inc mine, are you telling me that all the US ones from eZlock are the same?

Huge liability issue. Its simply unsafe.

[Burgerman]

I am not sure about the ezlock make. They may have off centre bolt, but the release 'face' may be a 90 degrees to the bolts centre. Ie not straight across. In which case they are safe. Anyone have a picture of an ezlock rear face?

Because here, this one looks safe.

Because the face is at 90 degrees to the bolt. As far as I can see.

[motoman]

I had a pic of the back of an EZ lock that I got off an ebay auction but I must have deleted it. But I do understand now what your saying about the rear face of the latch being 90 degrees. I looked at my EZ lock branded unit and mine is a few degrees less than 90 which would hold fine. Somebody better get this fixed or somebody is going to get killed.

[tomcmo]

I offer my thanks to everyone posting and I am glad that this issue has raised a debate around the design of these locks. I have contacted the manufacturer of my lock and they saw the videos. They said they had never encountered the issue before and that they bench tested an identical lock which did not release. They suggested filing the corner of the "L" of the lock to remove any surface wear "sloping" that may cause the release. I'm inclined to agree with BM in that the pivot positoning and/or jaw angles are incorrect. I drove in an original EZ lock for over 10 years with minimal maintenance and I had no issues with it whatsoever, and that was when I was younger, dafter and faster. These new clamps appear to overlook the subtle angles and placement of the EZ lock pivots and jaws which cause the locking action to be strengthened by increased pressure. I would love to get a close-up of an original EZ lock underside, anyone? I have the underside pic from ebay but it does not show anything conclusively and as previous posters have commented the pivots are in similar positions.

[Burgerman]

Trust me the angle will need to be about 5 degrees, to make it 90 degrees to the pivot bolt before its safe. They don't understand what they are looking at.

Any less than 90, and it WILL open if theres a sudden or high load. They do not understand the geometry. The chair is PUSHING that bar sideways.

I suggest you send them a link to this thread.

Filing yours isn't a solution, even if it stops you pulling it open. Because it will not be safe unless the whole part is filed by around 5 degrees. They need a re-design. Remember, I too can get my chair out of mine!

[tomcmo]

Completely agree with you BM. Having found a nice relatively high-res pic of an original EZ lock http://www.wheelchairvanoasis.com/Car%20Pictures/03%20chevy%20silver%20040.JPG the angle of the jaw is clearly toward if not exactly 90 degrees from the pivot.

[Burgerman]

For it to be safe, it MUST be either exactly 90 or steeper so it locks it shut under load. Yours is doing the opposite.

[motoman]

I sent a note to the guy that fixes my van to see if he will send a straight on latch pic from the back, as they have ezlock's in stock.

[Burgerman]

I think eZlock will be fine. From the pic I looked at they got it right.

[tomcmo]

Just to get my head around the locking action I have put together an altered image of my lock side by side with the original. I think that is the general ptinciple behind the orifinal EZ lock that increases the lock with the direction of the force, opposed to my lock that unlocks with increased force.

[Burgerman]

That's correct. That is one way to do this. That's what ezlock do.

On your altered image, that neither locks or unlocks under load. So the spring is adequate no matter how strong. The angle would need to be even more steep to hold it shut (positive locking) under load.

The other way is my altered image with pivot bolt central. They both result in the same affect, with zero opening or closing force - only more loading.

Original design = fail...

[tomcmo]

Quite coincidentally I found an EZ lock for sale 5mins from me today, lovely guy sold it to me for £10, first bit of luck I've had for a while. Pics of EZ lock mechanism no problem now. As we have established the EZ locks are safe due to the angle of pivot and jaw which can be seen clearly in the pictures.

[Burgerman]

SOMEONE should mention this to bekker?

Or someone will get hurt.

[ex-Gooserider]

Interesting...

Has anyone had a chance to look at the Q-lock plate to see if it has the same issue???

That's what I have in my van, and it hasn't let go of my chair yet, I haven't tried it on a hill yet though.

One thing that does somewhat suggest that it may be OK is that if I have any load on the mechanism, it won't release when I push the button - the green indicator light stays lit and the chair remains locked in if I try to back out with it locked and load the action. It then releases as soon as I give the chair any forward stick to take the load off...

(This happpens often if I'm charging the chair from the van - I hit the release and try to back out, the lock opens but the chair doesn't move under only 12V. By the time I get the moving plug back in, the lock release has timed out and locked again, so I back against the lock )

ex-Gooserider