cement mixer rotates too fast

Don't you mean "try it at 25 Hz"?

Don't think these are synchronous are they?

Fairly standard AC induction motor usually - although I have not looked at that particular one.

Its probably a moot point anyway - the OP was on HOH - so he is unlikely to ever see or respond the the thread again!

How to slow it depends on the gearing arrangement, whether pulleys (typical of old machines) or gear. Maybe show us how the motor drives the barrel on that one.

If all else fails the motor could be driven at reduced v & f or pulsed if it can provide enough torque. That can be done open loop rather than the old centrifugal speed governor technique.

NT

Do you need an exploded parts diagram ?

The motor is an induction motor, with a starter capacitor strapped to the side of it (25uF for 230V model). The wiring is not suggestive of "speed options", as you get on a central heating ventilation fan (which has four taps for speed). The electric motor runs at one speed (with "slip" as a function of loading).

The beauty of the Belle documentation, is figuring out what you own, and what diagram might pertain to it. There's apparently a gasoline version (after market?) of that thing too, as well as the notion of electric drive. And multiple model years, all hiding under the same SKU, making picking parts for it, a nuisance.

I could also find an example of a metallic worm gear for that thing. But there's no sign of that in the diagram above. The above has two levels of gearing.

Belt #46, wheel #45, cannot see pulley for other end of belt. Gear #34, ring gear 15 on drum.

Because of the ratios and sizes involved in those, I don't see home-retrofitting being a viable option. You probably cannot reduce the tooth count on Gear #34 without making it non-functional. And wheel #45, it might not fit if you were to increase its diameter a large amount. It would end up too big for the housing 4.

You could try looking for an induction motor with a different pole count. But I don't remember any "bargains" for motors the last time I looked.

Sometimes, you can find an electric motor you want, but the shaft size is wrong, or the shaft is keyed, or the shaft is the wrong length. Some of these things can be fixed, but again, at a price.

If you change the shaft speed, the forced air cooling velocity inside the housing will be reduced. For whatever that is worth. Motors come with various ventilation styles.

There isn't that much room for the electric motor in this case. You couldn't play the market for an "open ended" solution, like say, a motor with twice the power, but occupying a larger volume.

This isn't the same model, but it shows how complicated they can make their exploded diagrams. This larger model has several powering options. The diagram, again, shows no evidence how the powering options are called out (from a model numbering perspective).

All our posts are there, including the exploded diagram that Paul posted.

The diagram shows both pulley/belt and ring gear. The ring gear is not going to be practical to increase the ratio of. The pulley I can't see if you can get a smaller one onto the motor, if you can that would slow it some. I don't know what sort of speed reduction results from charging the thing with mix. Baby belle mixers aren't a type I'm familiar with.

In the end, if it's capable of turning at all with mix in, then it can be slowed by other simple means, but I'd definitely start by a) checking speed when fully loaded b) gearing it down with a small motor pulley as far as possible.

Once those are done, a pulsing driver or VFD would slow it further. But it would also reduce the motor's cooling fan speed, and that would need a workaround, ie a separate small high speed fan. A slower motor is the other option.

I'm a bit more familiar with much older mixers, but not a lot.

NT

Yup, but think how many times have you actually seen any kind of interaction with a HoH poster?

Many because they post to very old posts that the site decides to promote by some odd algorithm, and finding them when they return to

Don't you mean "try it at 25 Hz"?

There is a kind of exploded diagram in the manual I linked:

The speed is determined by the mains frequency and only varies slightly withe load. As it is with all induction motors.

Well, no. But aren't they just normal AC induction motors? Typically running unloaded at ~1450 rpm for a 4 pole version, only slightly slower when loaded.

As the speed of the rotor drops below synchronous speed, the rotation rate of the magnetic field in the rotor increases, inducing more current in the windings and creating more torque.

The ratio between the rotation rate of the magnetic field induced in the rotor and the rotation rate of the stator's rotating field is called "slip". "

And the label on the diagram to the right of it is labeled "inherent slip", meaning it's a principle of operation and not just an arbitrary measure of "mechanical load".

Paul

Of course there have been various other ways to drive them over the century plus they've been around.

By hand. Plus with a diesel engine. Forty years ago, electric mixers were unknown.

so you know little of cement mixer history. What's new.