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Very old Brent wheel repair question.


Standrew

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Hi! Recently I purchased an old Brent wheel on Craigslist. The wheel works great but the pedal speed control sub assembly (potentiometer) needs to be replaced. The wheel wouldn’t stop spinning very slowly with the pedal in the stop position, and the other day the potentiometer seized completely. I took it apart and was able to free it up by lightly lubricating the shaft of the potentiometer and working it for a few minutes.   This wheel is very old, I’m guessing maybe the first style Brent offered. It’s welded steel frame with the Brent yellow completely flat Formica top, no raised ridge around the edge. It has the double v-belt style drive with two narrow belts.  Control box is a small aluminum box with no labeling, just fuse, power light and on/off switch. No splash pan, or flange to mount one like newer brents have. The foot pedal is different from modern brents, the actual pedal is narrower than the housing assembly it sits in.

Has anyone replaced the switch in these pedals? It looks just like a standard j-type potentiometer, kind of similar to one in an old electric guitar volume knob. Would the older style replacement pedal Brent sells on their website for pre 2000 wheels work? I’m doubting it will because the speed control sub assembly in those looks very different. Any help would be great! The wheel works well and I bought and adapted a modern Brent splash pan to work on my wheel by attaching some large thin magnets to the bottom of the pan.  Would love to get the pedal working properly. 

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40 minutes ago, Standrew said:

Hi! Recently I purchased an old Brent wheel on Craigslist. The wheel works great but the pedal speed control sub assembly (potentiometer) needs to be replaced. The wheel wouldn’t stop spinning very slowly with the pedal in the stop position, and the other day the potentiometer seized completely. I took it apart and was able to free it up by lightly lubricating the shaft of the potentiometer and working it for a few minutes.   This wheel is very old, I’m guessing maybe the first style Brent offered. It’s welded steel frame with the Brent yellow completely flat Formica top, no raised ridge around the edge. It has the double v-belt style drive with two narrow belts.  Control box is a small aluminum box with no labeling, just fuse, power light and on/off switch. No splash pan, or flange to mount one like newer brents have. The foot pedal is different from modern brents, the actual pedal is narrower than the housing assembly it sits in.

Has anyone replaced the switch in these pedals? It looks just like a standard j-type potentiometer, kind of similar to one in an old electric guitar volume knob. Would the older style replacement pedal Brent sells on their website for pre 2000 wheels work? I’m doubting it will because the speed control sub assembly in those looks very different. Any help would be great! The wheel works well and I bought and adapted a modern Brent splash pan to work on my wheel by attaching some large thin magnets to the bottom of the pan.  Would love to get the pedal working properly. 

These have always been very hand built, how about measuring the potentiometer and replacing it?

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You have one of the 1st Brent wheels. I have owned two of them-the 1st one I bought From Brent himself.

That foot pedal will need replacing as the potentiometer is of a kind that is no longer made or lets say I could never find one and Brent gave up on them as well.

Its possiable to craft a nother typ and fit one in but it would be a oneof a kind thing. I had to replace the whole pedal with a mondern Brent foot pedal and they are costly-Its a straight  across rewire job.

That flat deck is easy to clean and when those wheels were new it came witha galvanized metal splash pan-they rusted out within about 10 years.

As noted the bearing /wheel head does not have the slpash pan flange-The new style slash pans (new meaning they have made them since the mid 70s)do fit around wheel head but float  around as it does not connect to anything.

The twin belt pully system is also not used anymore and the motor is a blue one without easy brush acess if they wear out. do not pull gthis motor apart let a. electric motor shop do any rtepairs on it when needed.

So all that said 

If the wheel works fine except the potentiometer replace the foot pedal with a new one (they come with a cord) and order the small wire (black plastic strain relief) with a new pedal. carefully replace . The control box is old style so do not break anything inside as its also not made anymore and very small for working in.

My wheel worked great like yours for about 30 years full time on it before I wore stuff out. The shaft bearing went second after a new foot pedal

The bearing on head went so I bought a new wheelhead which the twin belt pulley does not fit on so I needed new small pully on wheelhead shaft as well as new motor shaft pulley and new drive belt as well. The motor bearings went later and Brent back then sold me a new experimental motor for a song (they never used them in production) All That was costly stuff  except the motor but now that wheel is a modern wheel in all regards .

I have a friend i helped with same wheel about 10 years ago-when his motor acted up a local motor shop put in new bearings for cheap and new brushes so they are still serviceable by a motor shop.

Those belts last forever but if you ever need one Brent may still sell them -I may even have some. I have those old small pulleys  for sure.I bought another old one like mine about 15 years ago and sold it but it was running perfectly.

I can answer any more quetsions if needed.

 

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Bill- on the back of the pot is says r-450.  I’m guessing that’s the max resistance? My meter says ~390 ohms in the stop position across two poles. It’s about 26 ohms with the throttle open.  I’m only seeing 500 ohm j-type pots for sale. Think I’d be ok with one of those?

Mark- you said you bought a pedal from Brent that worked with one of your old wheels? Do you remember which one or if they still stock one?

thanks for the help

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39 minutes ago, Standrew said:

Bill- on the back of the pot is says r-450.  I’m guessing that’s the max resistance? My meter says ~390 ohms in the stop position across two poles. It’s about 26 ohms with the throttle open.  I’m only seeing 500 ohm j-type pots for sale. Think I’d be ok with one of those?

Mark- you said you bought a pedal from Brent that worked with one of your old wheels? Do you remember which one or if they still stock one?

thanks for the help

Hmm, I would try it as a last fix.

There should be some other pots to allow for fine tuning. I have a Brent later schematic (no doubt) below but it should give you an idea of the type of voltage divider often used in most speed controls. Given this pot works without a jumpy response now that you have cleaned it, you may be able to locate the other portions of this divider and perhaps, if adjustable, they need a little cleaning and adjustment as well.

Often the wiper of the pot corrodes and creates a dead spot or out of tolerance condition. Clean the wiper and a few turns back and forth often restores the pot to functionality. I would look for the rest of the voltage divider and make sure all are clean and exercised, then check your pedal adjustment. The original pot might be fine now that you have cleaned it up. 

All of thiese resistors or pots work together to provide an adjustable smooth control. The other pots may actually be the underlying problem.

Best diagram I can post here below, they have reduced the allowable picture size to near nothing. If it’s not clear, PM me and we will get you something with greater clarity.

Finally, if you are stuck a picture of what you have would be handy.

E50C7471-8147-4171-91F5-3B05327BD0FB.jpeg

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4 hours ago, Bill Kielb said:

Hmm, I would try it as a last fix.

There should be some other pots to allow for fine tuning. I have a Brent later schematic (no doubt) below but it should give you an idea of the type of voltage divider often used in most speed controls. Given this pot works without a jumpy response now that you have cleaned it, you may be able to locate the other portions of this divider and perhaps, if adjustable, they need a little cleaning and adjustment as well.

Often the wiper of the pot corrodes and creates a dead spot or out of tolerance condition. Clean the wiper and a few turns back and forth often restores the pot to functionality. I would look for the rest of the voltage divider and make sure all are clean and exercised, then check your pedal adjustment. The original pot might be fine now that you have cleaned it up. 

All of thiese resistors or pots work together to provide an adjustable smooth control. The other pots may actually be the underlying problem.

Best diagram I can post here below, they have reduced the allowable picture size to near nothing. If it’s not clear, PM me and we will get you something with greater clarity.

Finally, if you are stuck a picture of what you have would be handy.

E50C7471-8147-4171-91F5-3B05327BD0FB.jpeg

Ok yeah I see in this schematic it shows the three pots in the pedal assembly on the newer wheels. A speed control plus one high and one low speed pot for fine tuning. I opened up my control box and found there was a small pot in there which did allow me to adjust when the pedal starts the wheel turning. Great advice. Pretty basic control box inside, some small capacitors and diodes and not much else! Looks like the newer Brent wheels have gotten a bit more advanced. I was considering eventually upgrading all the mechanicals on the wheel with new from Brent someday, since they offer basically everything but the actual wheel frame. But the cost might be comparable to buying a new wheel. Thanks for the help!

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Brent does not sell or have those pld foot pedals like yours which is a bit different shape and much lighter than all the newer bRent footpedals taht they started using int the later 70s. My foot pedal is just like the new Brent styles and they work fine on old wheels like yours . If you find a slider mechanism with a pot let us know the source please.

The  wheel pedal even the old ones have the red and blue speed adjusment pots on bottom of foot pedal-they are part of the slider an all in one deal (see the Brent videos pinned at top of main equipment page on Brent wheels)

These only set high and low speeds whereas the slider does the in between speeds and has a slider arm which is white plastic on yours (new ones are black colored)

You can buy just the slider  with pots and it may fit in your old pedal-talk to a Brent technician before buying. They are a bit different but may be adaptable

Its been to many years for me to recall-I may still have broken one and will look. to see how compatable they are

If I recall the new Brent pedal has way more rooom inside than your old one so I doubt the new parts will fit.

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Yeah my foot pedal has a rotary potentiometer inside instead of a slide type.  After making an adjustment to the resistance inside the controller box, things are now working pretty good.  I have located some surplus Allen bradley rotary potentiometers on eBay, the trick is just finding one with the right length shaft, and I think I’ll order one for spares should this old one ever seize up again.  As for buying a newer style pedal with the slide type pot, I think as long as the voltage to the pedal is the same as newer models, the newer style may work with my wheel. They’re just so ridiculously expensive! Just for the heck of it, I added up the cost of all the parts I would need to make this old beast a modern Brent wheel as far as the working parts, basically everything but the frame. It’s about $1500! So not really cost effective considering that’s close to the price of one of brents new top of the line wheels. Sounded like a fun project but nope!

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Here’s a picture of the wheel and the pedal. As stated, I adapted a Brent splash pan to work on my wheel by attaching two magnets to the bottom of the front piece. I just drilled through the pan and used one stainless button head screw each and bonded washers to seal the screw hole from leaking water. I may fabricate my own flange piece to attach under the wheel head for the splash pan when I go back to work and have access to the machine shop there, but the magnet system works quite well really. Doesn’t move at all. 

A50FD5E2-0B0F-466A-929C-7CAB2E637998.jpeg

A29776E6-A916-421B-9111-C8DB12BF831C.jpeg

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Never seen that rotary potentiometer in a Brent pedal.

My model C wheel is the same as your wheel same deck except a 14 inch wheel head.When I bought a new wheeled about two decades ago I got the 14 inch head.

Can you post a better photo of your controller on the side of wheel.Is your motor Blue in color?

The new style foot pedal will work just fine with that controller I'm pretty sure.

There is no reason to convert to anything as long as its works. The  rotary potentiometer  is the weak link. The belts and pulls will last a lifetime -the wheel head bearing can take 30 plus years of full time pottery production work as  well.

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There is a slight noise that comes from the wheel head at faster rpms. I pulled the pulley off the bottom and removed the whole assembly today to check it out. Definitely a little bearing noise. No noticeable looseness in the bearing. Also there’s a little wobble when it turns, like .5 mm or less. Very slight. I guess if it becomes a problem I can buy a new wheel head assembly. Just have to lathe the inside of the pulley to 3/4” and broach a new key way in it. For now I’ll just keep running with it. 

847B6FCC-AA1D-487A-9C53-00BC4FA94E22.jpeg

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6 hours ago, ronfire said:

I have had luck cleaning potentiometer with spray electrical cleaner or sometimes Brake Clean.

 

Yeah that’s a good idea. I blasted it with som MAF cleaner. I think the little electrode might be a bit worn too. I think this wheel has some miles on it. 

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I've seen several wheels with that pedal. It's not a very durable potentiometer IMO. They get out of alignment somewhat easily. If you're willing to put some money into the wheel, I'd upgrade to a new pedal. First start adding up all the different things it's going to need and see if any of it is really worth it.

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I think the only part that could be replaced without an investment of money or labor would be the pedal. If I wanted to change the wheel head assembly to a new one, I’d have to replace the motor, belts, pulleys, pedal, and control unit as well since all newer Brent wheels have gone to 3/4” shaft sizes and my wheel is 5/8”.  I think for now I’m going to keep using it as it stands and maybe order a new wheel head assembly from amaco some time. I can machine the pulley to fit a keyed 3/4” shaft and with a new potentiometer or whole new pedal, the wheel could maybe go for another 40-50 years! It’s pretty impressive how long it’s been running in probably it’s all original state. 

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If you screw up the pullies while machining, I may still have my orginal one you can have if you need it. I assume you are this side of the pond (ocean)I know I have the small pully and I keep everything so the big one has to be around as well.

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4 hours ago, Riced2020 said:

Does anyone know how many ohms each of the potentiometer  in the foot pedal pull.  Can buy all the parts to rebuild the pedal but have to know ohms to buy right parts

. It

Probably best just to measure them. The schematic above may not apply to your version and the trim pots are unlabeled in the diagram.  The pedal pot says .7 meg but I would measure to be sure. Measure across the two non wiper leads. Often they will be stamped with a value on them as well. The problem with measuring is you might have to disconnect them from the circuit else risk getting a false reading. 

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I may be wrong, but doesn’t amaco sell the whole speed control assembly in their new style pedal for around $90? I think it consists of the slide potentiometer for speed control and the two trim pots for high and low tuning. May be a direct swap. Otherwise, yeah as Bill said, have to measure resistance at each potentiometer and best practice is to do it unwired. 

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