Hobart A 200 FT not mixing when under load, operates when empty but makes humming sound when load is added, what could be the cause

It could be 2 things.

Either a shear pin has sheared and the paddle is sticking at the same spot.
or
The is a nylon cog inside that has lost teeth and it sticks there.

The only way to diagnose is to take it apart. It is a very MESSY job full of grease and oil.

https://www.google.com/search?q=hobart+mixer+hl200+parts+manual

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Try having the planetary nut(s) less tight. From what I've read this model is very sensitive to the main shaft being tightened too much. I'm in the process of rebuilding mine and I screwed this up. Sounds like you did better if it's largely working. Let us know what you find.

Is the humming noise the sound of the motor straining to turn without moving (it won't last very long like that) or the sound of the motor turning but not operating the paddle?

I'd say you're most likely overloading the mixer. This mixer, and others similar in size, are frequently overloaded by people making pizza dough. If you are making dough, keep in mind the A-200's capacity is 9 lb. of 40% A.R. pizza dough, mixed for 5 minutes maximum. If you need to mix longer, the batch must be cut down even smaller, but I don't even know if you're mixing dough.

Try running the mixer unloaded (i.e. nothing in the bowl) for ten minutes or more and see if it gets hot. If it still gets hot, the motor's start circuit (varies depending upon age of the A-200; Hobart used numerous motors in the A-200 over the years, incorporating different starting circuits) most likely has problems. If it doesn't get hot when operating unloaded, then you're probably overheating the mixer by overloading it.

Short answer: something is worn/broken inside the mixer's transmission.

Longer answer:

Since none of the three gears operate, the problem is most likely on either the worm gear shaft (probably the brass worm gear itself) or the "transmission shaft" (ironic name as all three shafts could be called transmission shafts). If you're up to the task of disassembling the transmission, which is a very messy task, you'd probably find the problem on one of the two smaller shafts inside the transmission. You'll most likely find either a broken key or worn brass worm gear. Both of these items may have enough holding strength to operate under very light loads (such as an empty bowl) but slip once a load is presented.
Also check the planetary key. Remove the planetary by removing two nuts on the underside of the transmission, where the attachments attach (careful, as the whole thing will drop once the second, thin nut is removed). You will find a long key on the shaft (or in the planetary gear, whichever one it sticks to). Make sure it's not broken, and re-attach the planetary.

You have killed it by overloading the bowl. Hobart recomends no more than 65% bowl capacity on doughs & 75% on batters or icings. Replace the motor or the whole unit

Ist check your agitator shaft for looseness. the shaft you put the beater on. wiggle side to side. if tight no play. If in first its quiet but you can here a grumble under load but second gets louder. and third even louder. If the shaft is tight. your gears down there are warn. you can take that all off with the two nuts underneath. and check the grease on the gears but even with new grease on them it most likely stay loud. grease it with hobart grease from your loacal hobart for the A-200 planitary not the transmision they also fve grease for Trans. if you can take the noise run it that way if not decide which arm & leg you want to give hobart for new gears.

7.8 sounds a little high. I'd inspect the GREASE in the unit. Just take off the top cover and then remove the dust cap. The grease in a D-300 is a really thin grease. It lays in the gear case. If things look dry, I'd consider tearing it down, cleaning it up, and repacking it. Get the grease from Hobart. The wrong grease will stress the motor futher.

http://www.acerestaurantequipment.com/pdf/mixerscapacity.pdf

http://www.hobartlink.com/extranet/extranetmanualsandcatalogs.nsf/08082CF4BE829A3C852568E1006A9A00/$File/F-19118%20(07-94).pdf

To Whom it May Concer: At the school I work we have a Hobart D-300 Mixer. When we mix bread dough it pulls alot of current and trips the breaker. The max current draw on the name plate is 10.1 amps. I have seen the current go over 30 amps during the mixing process. Under no load the mixer pulls 7.8 amps. I dont have any information about this machine on paper and I can only go so far with troubleshooting.
My questions to you are: Is it normal for the mixer to draw 7.8 amps under no load? And is their a manual online I can look at so I can check the oil levels and make sure I do not have a low oil/needs greasing condition.
Thanks for your help and time,
Kenneth Clayton
Spartanburg Schools Dist#2

Does the mixer work in any other speeds?Are you mixing pizza dough and in what speed?I service these mixers alot--i work for hobart.It sounds to me like you have a sheared key on one of the shafts.The mixer doesnt have a clutch.