GR3750 Transfer belts stop at speed 3+

[avidgamr]

We had this problem before but my then manager managed to fix it somehow but it had a new problem afterwards (loose connection) and wasn't used for years. I fixed the connection problem thanks to the helpful advice here but now the problem suddenly came back after like 2500 sheets? Same as before- runs fine at speeds 1 and 2 but when you hit speed 3 or higher, the transfer belts suddenly stop and jams occur. He told me what he did but that was like 4 years ago and now I don't remember what he said the problem was before (seems to be the same problem again?).
I've searched the service manual and see the description of how it works on page III-1. Just wondering if any one has had this problem before and what the solution was before I tear into it... Loose gear? Loose suction pulley shaft? Curious of ideas/advice before I open it up (as I've never opened that section up before)...

[Iowatech]

Re: GR3750 Transfer belts stop at speed 3+

We had this problem before but my then manager managed to fix it somehow but it had a new problem afterwards (loose connection) and wasn't used for years. I fixed the connection problem thanks to the helpful advice here but now the problem suddenly came back after like 2500 sheets? Same as before- runs fine at speeds 1 and 2 but when you hit speed 3 or higher, the transfer belts suddenly stop and jams occur. He told me what he did but that was like 4 years ago and now I don't remember what he said the problem was before (seems to be the same problem again?).
I've searched the service manual and see the description of how it works on page III-1. Just wondering if any one has had this problem before and what the solution was before I tear into it... Loose gear? Loose suction pulley shaft? Curious of ideas/advice before I open it up (as I've never opened that section up before)...

Just need a bit of clarification so we don't go on a wild goose chase, are the transfer belts you speak of the three belts that transfer the print paper from the drum to the exit tray?
Sorry, I worked on Riso brand duplicators for quite a while and learned that language, but that can lead to misunderstandings when trying to help others who have not.

[jermyth]

Re: GR3750 Transfer belts stop at speed 3+

If its the exit transport belts in suction unit there are possible causes.
There is a set screw on a gear in the suction section that likes to back out. You have to pull the whole suction unit to get at it.
The second possibility is a one-way gear in the clutch gear pack that drivers the suction section. See fig 17, clamp pressure control area in the parts book and chapter 3 section 13, suction clutch in service manual.
Good luck.

[20gaugeO/U]

Re: GR3750 Transfer belts stop at speed 3+

Ya what Jermyth said

[avidgamr]

Re: GR3750 Transfer belts stop at speed 3+

Just need a bit of clarification so we don't go on a wild goose chase, are the transfer belts you speak of the three belts that transfer the print paper from the drum to the exit tray?
Sorry, I worked on Riso brand duplicators for quite a while and learned that language, but that can lead to misunderstandings when trying to help others who have not.

Correct, the three belts that bring the paper out of the machine that are located after the drum...

[avidgamr]

Re: GR3750 Transfer belts stop at speed 3+

If its the exit transport belts in suction unit there are possible causes.
There is a set screw on a gear in the suction section that likes to back out. You have to pull the whole suction unit to get at it.
The second possibility is a one-way gear in the clutch gear pack that drivers the suction section. See fig 17, clamp pressure control area in the parts book and chapter 3 section 13, suction clutch in service manual.
Good luck.

Thanks for the reply. I was afraid that's likely what it was. My money is on that gear.
Related question... Can I put a drop of loctite (blue) on the gear screw (if that's the culprit) when I re-tighten it? Or would that be a no-no and cause a major problem later? What do you guys recommend?

[20gaugeO/U]

Re: GR3750 Transfer belts stop at speed 3+

Loctite is fine on any screw that backs out. Good luck

[avidgamr]

Re: GR3750 Transfer belts stop at speed 3+

The screw on the gear in the suction unit was loose but was not the problem I'm having...
jermyth, Can you give more details on the second possibility? I'm looking at the manual, pg. III-22, but I'm not understanding which gear. If you're referring to the gear that protrudes inside the Riso unit (the gear that meshes with the Suction Unit gear), it spins freely one direction but doesn't seem to move the other way (spins freely in the exit direction to assist with paper jam removals?).
Thanks!

[jermyth]

Re: GR3750 Transfer belts stop at speed 3+

There is a gear in the suction gear assembly that is a one-way gear. Its the gear that is in front of the clutch in the assembly. You have to take the assembly apart while it's still in the machine because there is a belt running through it. Not fun and has been years since I've had to dig into that. If you have the parts manual see fig 17 clamp-pressure control, it's part #18. You can try cleaning the one-way with alcohol and qtips, but replacement is best.

Good luck.

[avidgamr]

Re: GR3750 Transfer belts stop at speed 3+

There is a gear in the suction gear assembly that is a one-way gear. Its the gear that is in front of the clutch in the assembly. You have to take the assembly apart while it's still in the machine because there is a belt running through it. Not fun and has been years since I've had to dig into that. If you have the parts manual see fig 17 clamp-pressure control, it's part #18. You can try cleaning the one-way with alcohol and qtips, but replacement is best.

Good luck.

I guess I don't have the parts manual. I was looking at the "Technical Training Manual"... Do you happen to have a link?

Would this cause my problem to random? I've noticed sometimes it will run in faster speeds with no problem. Randomly works fine or the transfer belts stop and cause a massive train wreck inside the machine. Weird problem...
On a related note, I'll bring my camera to work Monday and try to get a video of the "train wreck" in progress; perhaps that would help in diagnosis?

[Iowatech]

Re: GR3750 Transfer belts stop at speed 3+

I guess I don't have the parts manual. I was looking at the "Technical Training Manual"... Do you happen to have a link?

Would this cause my problem to random? I've noticed sometimes it will run in faster speeds with no problem. Randomly works fine or the transfer belts stop and cause a massive train wreck inside the machine. Weird problem...
On a related note, I'll bring my camera to work Monday and try to get a video of the "train wreck" in progress; perhaps that would help in diagnosis?

I think the gear jermyth is talking about is in the clutchpack that is found in the back of the machine (if looking at the back of the machine with the cover off, it is on the lower left hand side behind the rear power supply). There is a long skinny toothed belt that drives that assembly. I think that unit exists because there was a collator that could be added when the machine was new.
I used to carry that clutchpack as car stock, and if possible you should replace the entire thing if the gear I'm describing is the problem.
And here's the standard warning if you do remove the back cover of that machine: there are many sharp edges and really strong springs back there that will harm you if you don't pay attention. So please be careful.
And the reason the problem is random at the moment is due to a reason that can be a mystery to us, too. Sometimes the one way unit loses traction with the gear it is installed in, but not entirely. Sometimes the shaft the one way is on wears to the point it can't always get a good grip, but still does. Or the one way mechanics could be full of gunk. Or something else. It's actually mostly impossible to give you the reason for that without actually seeing the machine. Then it's easy.

[20gaugeO/U]

Re: GR3750 Transfer belts stop at speed 3+

Ya what Iowa said. Been a long time since messing with one of these but clean the clutch faces as well with alcohol. Even if you are unsuccessful the machine is still kicking out at 60 or 80 ppm in speeds 1 and 2.