Problems with the speed of my wheel

[Amitha]

Hello, 

I have a shimpo RK 55 which is pretty new. I’m here because I seem to have a problem. When the wheel turns at a lower speed it slows down with the slightest amount of pressure. Happens while pulling too. I’ve used other RK 55 wheels and haven’t had such a problem. Is this normal? If it isn’t, what can I do about this? 

Regards, 

Amitha 
 

[Hulk]

Hi Amitha!

I believe that model is belt driven, and isn't a particularly powerful wheel, likely toward the low end in sustained torque potential, but still very serviceable? From what I've read, strong enough for smaller pieces, perhaps up to 2000 grams or so, but even then, requiring some patience for centering and big pulls, particularly with stiff clays.

Any road, if you're experiencing a marked difference from your wheel and others of same specification and model, try checking the condition of the belt and the belt tension - any slippage there? Belt slipping is often accompanied by unique sounds - perhaps squealing of the belt on the pulley, but not always, and subtle variation of motor noise as it relates to the rotation speed of the wheel, for if the belt slips, the motor turns faster, eh?

If there's no slippage, can you throttle the power to keep the wheel speed up - is there more umph available? If so, the controller may have an adjustment for that - some of the boards have provision to compensate for load in order to maintain rotational speed.

Other forum readers who have direct experience with your model might chime in later...

[Piedmont Pottery]

It sounds like a loose belt.  If I remember correctly you tighten the belt by taking of the splash pan and loosening the 4 bolts underneath the wheel head just a bit, then a spring tensioner will adjust the tension.  Tighten the bolts back down and you should be good to go.  Be sure not to take the bolts all the way out, just loosen them so the tensioner can engage.  There's probably a description of the process in the owner's manual.

[Ian Bee]

I have a similar issue. At really low speeds the belt sputters. It engages then disengages. Once you put a little juice on the pedal it evens out. I have 3 wheels and replaced all their belts a couple weeks ago. Maybe it’s the pedal? Please advise

[Amitha]

Thank you all for your responses! I have checked with my buyer and he also tells me that this is normal.  
However, I’ve done tightening and loosing of the bolts too. This is helpful 

[Min]

On 5/4/2021 at 3:29 PM, Ian Bee said:

At really low speeds the belt sputters. It engages then disengages. Once you put a little juice on the pedal it evens out.

This is exactly what my old Shimpo Master did when the controller was slowly going.

If this is a mechanical issue (belt tension/slippage) at low rpm machinery doesn't transmit as much torque as it would be able to at higher speeds.

[MrsFCB]

Hello, I've recently bought a second hand Podmore & Sons model 6718 wheel. It has a lever speed control with a speed control circuit box internally. When I got it home and tried to use it I found that the wheel slowed when I applied pressure to center a 500g ball of clay.  

I've had the motor checked, by a local motor rewind company,  they say it seems fine, and when connected to power and bypassing the speed control board the wheel maintained speed when I applied pressure. The motor Co think the issue is with the speed control board.

So  my question is what should I look for in replacing the speed control board (the existing on e is obsolete). OR is there perhaps a foot pedal control which can be wired in without a separate speed control board. i.e. direct to the motor or would a separate control or other component still be needed?

 

Any help gratefully received

 

The motor is a Parvalux  SD 12,  geared  DC. The spec panel gives the following info:

Volts: 200/220, AMPS 1.4 ; HP 1/4; RPM: 4000; WATTS: 190 

Gear spec: 

LBS/INS 65; RPM 200; RATIO 20/3; CM KP 60 (I think, but its tricky to read).