Headlight pod unable to stay open

[hspeck]

Hi, recently had some problem with my left(passenger) side headlights. The headlight pod is unable to stay open. 

I discovered that when the motor is connected to the long rod, I am unable to lift the pods manually by turning the knob. However, if I disconnect the long rod, i can see that the small rod at the motor side is turning. 

I was also able to push the headlight pod up simply by pushing on the long rod. 

I have opened and check the motor, all gears are intact and good (just replaced them 3 months back). However, I realised that I could turn the rod at the motor.

Has anyone encountered the similar problem with the motor? 

 

 

[Escape]

Did you check the ptfe rollers inside the big gear? I can't tell from the pictures. If they fail, little or no torque will be transmitted. Might be enough to turn the small lever with no load, but certainly not enough to open the pod.

Filip

[ramjet]

I was going to ask the same thing Filip.

Inside the opaque nylon gear are three nylon/ptfe? rollers. You should find that the gear will separate with both shafts in it coming away with a section of the drive.

If the rollers are shot, you need to replace them.

[Escape]

@ramjet now you've mentioned it, not sure if they are indeed ptfe or just nylon, like the gears. I never understood why such a complicated construction that's prone to failure was needed, instead of a simple connection between the shaft and main gear. If it's to allow a bit of play and not load the motor shaft, large splines would accomplish the same and last longer.

Filip

[andydclements]

I think they're Delrin (aka Polyoxymethylene), but agree it doesn't explain why they exist, perhaps they have a role of shock absorption, which would otherwise destroy the toothed plastic gear. That's just a guess.

[ramjet]

Very similar to a cush drive on some motorbikes. Allows for a slight amount of takeup before loading up all the other parts.

[ragingfool35]

i suspect they are sacrificial much as the inserts of many other types of couplings is such as Lovejoy, etc.  Since they are plastic with a plastic wheel it is less likely they absorb shock as many inserts do.  I put aluminum gears in mine so the plastic torque pins probably serve both purposes now

[Escape]

12 hours ago, ramjet said:

Very similar to a cush drive on some motorbikes. Allows for a slight amount of takeup before loading up all the other parts.

To get the motor started without drawing too much current (to which the control box could react), that would be useful I guess. And easy/cheap enough to replace, so maybe not too bad after all.

[hspeck]

On 18/11/2019 at 18:15, Escape said:

Did you check the ptfe rollers inside the big gear? I can't tell from the pictures. If they fail, little or no torque will be transmitted. Might be enough to turn the small lever with no load, but certainly not enough to open the pod.

Filip

Which are the ptfe rollers? The 3 small round thing? 

I did replace the big plastic gear and the 3 small round part inside and also applied a generous amount of grease. 

I was able to turn the small rod with my hand though.. The one arrowed in the 1st post. I am thing I should not be able to do that.. 

 

[andydclements]

This may be a very stupid question, but is the screw gear of the motor shaft actually engaging with the big plastic gear?

The combination of the three cylindrical rods (circled in the image above) should lock the big plastic hear to the shaft on which it sits, so with the screw gear engaged you should be unable to turn that shaft.

[Escape]

Indeed, you shouldn't be able to turn that small rod. If it moves with respect to the gear, the rollers (3 small cylinders) are probably shot, so you'll have to replace them again. If those are OK, but it's turning in the housing (with motor bolted up) look at the engagement of the gears and the motor, as Andy says

Filip

[hspeck]

19 hours ago, andydclements said:

This may be a very stupid question, but is the screw gear of the motor shaft actually engaging with the big plastic gear?

The combination of the three cylindrical rods (circled in the image above) should lock the big plastic hear to the shaft on which it sits, so with the screw gear engaged you should be unable to turn that shaft.

The screw gear on the motor is engaging the big plastic gear. When i turned the rod the big gear was not turning.

I can actually turn the small rod with one hand while holding onto the big gear with another hand. Not free turning but with a little effort. It seems to catch at a certain point but if I tried to turn it again the resistance became lesser after that point. The rollers are like new when I opened them last week.

I am wondering what is inside securing the rod.  I have never read of this part failing though.

I will have to remove the motor again next month as I will be in Italy for my holiday from tomorrow ...  will try to update again then.

Thanks guys.

[andydclements]

In that case, does the rod turn relative to the metal casting? It shouldn't but I suspect that's at fault. The rollers act to lock the casting to the big plastic gear, so short  of the rollers some how moving out of our plane of existence,  them being there when you assemble it means the casting is  not turning (beyond taking up slack) relative to the gear.

[hspeck]

On 22/11/2019 at 16:16, andydclements said:

In that case, does the rod turn relative to the metal casting? It shouldn't but I suspect that's at fault. The rollers act to lock the casting to the big plastic gear, so short  of the rollers some how moving out of our plane of existence,  them being there when you assemble it means the casting is  not turning (beyond taking up slack) relative to the gear.

Sorry for the late reply. Just came home 2 weeks back and had been busy. 

Yes, the rod was turning when I held on to the metal piece. 

I replaced the piece and it is now working. It used to be intermittent but works really well now, so i guess it was starting to loosen some time back. 

Really glad i have my lights back.