Briggs & Stratton 5hp generator

Couldn't resist this generator! 2.3kw alternator driven by a 5hp Briggs & Stratton Industrial/Commercial engine which has a cast iron bore.
Good compression and runs well but won't take a load as the governor requires 'attention', don't know exactly what but it looks like a nice bunch of linkages and springs and what looks like - bits missing!


Was supposed to be a winter project but it is now being dismantled for a look.
Lots of aluminium corrosion but luckily it's only light and comes off easily but will be quite time consuming.
I decided to separate the engine from the generator so they could be tackled individually, however I was in for a bit of a suprise. There is no rotating coils fed by slip rings and although I have removed the generators fan, end case and windings it appears to be an extension of the crankshaft? I was expecting a spline or some means of removing the generator shaft from the engine. The generator end case is bolted to engine crankcase followed by the windings and the outer end case with bearing.
Has anyone come across similar or any suggestions as to how it might come apart?

Alan

Quite common for close coupled generator sets, some Lister generators only had the outer bearing assembly with the other end relying on the engine crankshaft.

Maryalice

Thanks, this, as you suggest has the generator's end ball race the other end uses the engine's crank bearing (other end to flywheel)
But I can't see/understand how it was assembled so I can separate them! Have to have another examination tomorrow.
It must come apart - it went together!

Alan

The joint must be in the engine casings, it might be part of the crankshaft.

Maryalice

Did a bit of searching and have found other B & S engine/generators that have a male taper on the end, the generator shaft fits onto this and is pulled to it by a long bolt that goes right through the rotor shaft.
However I can believe my engine has the taper there is no visible means of holding the rotor on!
So dismantling will be limited, there are no leaks from sump areas and bearings feel good so will leave that as is.
Been cleaning up topside and with head removed once again the original honing marks are still visible and no scoring so have decoked ports/valves, ground them in and found clearances were still in limits!
I have engine casing and other sheet metal parts in my improvised electrolysis tank (washing up bowl!) as the internal surfaces of the parts had no paint on and consequently were fairly rusty. A result of only being painted after assembly.

Alan

I did a similar project a while back on a 1972 genset. B&S 4HP with a 1.5KVA output.
Had the same problem finding a way to part the shafts and gave up, not wanting to cause damage.
here is a link to the Thread on it back in 2014 if interested-  72 Genset
Regards

Anglo Traction wrote:I did a similar project a while back on a 1972 genset. B&S 4HP with a 1.5KVA output.
Had the same problem finding a way to part the shafts and gave up, not wanting to cause damage.
here is a link to the Thread on it back in 2014 if interested-  72 Genset
Regards

How did this work out in the end?

I've a feeling I'll have similar issues when I delve into my Allam Minigen.

Thanks - interesting link, did it generate? Looks like it should have done.
Not come across generators without sliprings to energise the rotor although not all that familiar with the different designs.
Didn't want to damage anything so have started to reassemble. Came to the conclusion that the rotor must be loctited to the shaft!
Still haven't received a reply from the generator manufacturer (Geko, German) and have today emailed Briggs in the hope that they can shed some light. I would like to separate the rotor to at least fit the new case gasket and shaft oil seal (not that they leak)
These little engines have cast/forged crank's and I don't believe it would be long enough to secure a rotor on - there must be a join!

Alan

After persistent searches I eventually got a reply from Geko who made the generator and it seems that the crankshaft and rotor shaft are held together with a length of studding! They also sent drawings of the two shafts being unscrewed - using pipe grips on the rotors shaft! Ultimate butchery I thought!
Anyway as there were no leaks from the inaccessible area I have left well alone and have reassembled everything, except the governor linkage.
Trying to find drawings showing in particular the governor spring has been an ultimate investigation as there are just so many variants. Found a new friend in Chicago who actually had the exact same set up engine and kindly photographed the assembly so I could establish what was missing, I am now waiting on the correct governor spring as the one I bought previously was about 3 times the length required.
Photo of where we are at moment, minus spring!

Alan

Hi Alan, that seems to be an interesting engineering approach to the problem of connecting the crank to the rotor. I can only assume the studding is high tensile and precision cut. I would also imagine the two faces of the rotor shaft and crank shaft are machined flat to provide square surfaces to ensure the extended shaft runs perfectly true! I wonder what torque the shaft is tightened up to and are both ends right hand thread or is it one of each?

It's good to see your investigations and perseverance has paid off, providing the information you needed. This can now be shared with others, who may come across a similar situation in the future. Well done with your efforts, it is looking good and with the assistance of your contact in America it should be a relatively easy project to finish.

Neil.

Thanks Neil, I know it's a relatively 'modern 1987' unit it appears quite well made and the fact that the generator doesn't employ any brushes gives it something less to cause problems!
Anyway, spring turned up today, stronger than I had imagined, removed cowling and it was fitted in minutes.
Petrol with a dose of 30 grade oil in went in the tank and after 3 or 4 pulls it was away! Choke eased in and it was running well.
Frequency meter measured it as running fast at 58Hz from the generator (50Hz @ 3000rpm) so adjusted the governor and left it at almost 52 with no load and let it warm up. Gave it a 1700w load and was pleased at its response from the throttle increase required, pretty instantaneous. Frequency down to 49 and a bit.
Quite pleased with it, after the running of almost an hour plug colour was good and will recheck head bolts once cold. Glad I didn't attempt removal of rotor but at least we know how it comes apart and shafts are located together using a taper (right hand thread in both)

https://youtu.be/TaRAVIO2pco

Alan

As an American build could it not be 60Hz, whats the voltage at 50Hz.

MaryAlice

maryalice wrote:As an American build could it not be 60Hz, whats the voltage at 50Hz.

MaryAlice

Probably built for the UK market so would be set for 50Hz, I've had a couple of B&S engined generators and they were 50Hz.

Definitely a 50Hz generator, says so on the plate. 230v 10 amp 2.3kw 50Hz @3000rpm. Same rating as yours robotstar5 - looks a later version of engine?
Watched several YouTube's of similar and when it first ran @58Hz I started to wind it up to 60! then engaged my brain cell.
It doesn't use any form of voltage control so unloaded it is about 260 and loaded was dropping to 220. Have to do some measurements to find what load drops it to 230.
It isn't designed with a 'tickover' setting on the control panel which I personally would like and I suppose it could be modified.

Alan