Shire 50 engine fan belts

[Barmpot]

I have a Shire 50 engine fitted with both 50a and 230a alternators. the engine has done 600 hours from new (fitted 2012). On starting to recharge batteries there is a high load on the 230a alternator taking around 150 - 160 amps. When on this high load the belt slips like mad. Same thing when cruising and her ladyship is using the washing machine, as soon as it needs high load the fan belt slips. I have been through 5 fan belts since July 2014.

Has anyone seen similar problems as Im sure that the 50 has only been having the 230a alternator since around 201.

[Alan de Enfield]

Personally I think you are on a hiding to nothing trying to drive a 2500watt (230a) 12v alternator, You would be better off using a Travel Power (2500w - or bigger) that produces the 220v directly for the washing machine.

 

Alternatively increase the size of your battery bank and run a 100a alternator - presumably your inverter is already of sufficient size.

[bigste]

As a retired and qualified engineer I'd suggest your setup is not fit for purpose. With an alternator that size as well as a second smaller one you should have a toothed belt similar to a timing belt. If that is not practical I suggest you personally visit a belt/bearing stockist and ask for advice. I suspect there may well be a better belt you could use. An alternator that size will need a tremendous amount of torque to turn it.

[OldGoat]

I'm not familiar with Shire engines but Barrus' site indicates that they use Poly-V belts - which is about as good as it gets.

Assuming that they are correctly adjusted - which is easy for you to do and check then the solution is likely to be:-

 

Run the engine faster when charging say 14-1500 rpm

 

Running at tickover - which is what most folks do - to cut down engine noise not only potentially damages the engine but increases the wear on the belt.

I've looked at an engine manual and seen that the alternator pulley is fixed directly to the 'fanbelt' pulley which itself relies on a small key to bear the load. In time that will fail and your crankshaft will be junk. Been there...

 

Alan-of-Enfield is right in saying that a travel power is better - but its still needs to be powered - so my suggestion still applies.

If there's a lot of black dust around - get a new belt adjust it as recommended, then run the engine faster.

 

Bigste - is correct but his comments only apply if you are using a normal V belt - if you are (and my assumption is wrong), then a standard A section or even a B is wrong - it should be twin belts. They always slip....

 

 

[Alan de Enfield]

 

Alan-of-Enfield is right in saying that a travel power is better - but its still needs to be powered - so my suggestion still applies.

If there's a lot of black dust around - get a new belt adjust it as recommended, then run the engine faster.

 

 

 

 

Thank you - but my point is that a 2500w 220 volt 'alternator' (producing 10 amps) will be a fraction of the load that a 230a 12v alternator demands.

[Stormbringer]

Try Ed at FC Marine, he specializes in alternators and belts and did a great job on my mates Barrus twin alternator set up.

He has some info about what he does on his website.

[Tony Brooks]

 

Thank you - but my point is that a 2500w 220 volt 'alternator' (producing 10 amps) will be a fraction of the load that a 230a 12v alternator demands.

 

 

Why? Apart from possible efficiency differences. 746 watt = 1 hp so it does not matter if its 240 volts at 10 amps or 12V at 200 amps, it is still the same horse power.

 

What have I missed?

[forsberg]

New problem or old? Belt type/ Original spare part?

[DaveGood]

I,d use a steel ruler straight edge to check that the two pulleys are actually square and true to each other, they don't have to be out by much to eat belts.

 

What sort of belt ( do you have a part number) is it?

 

DaveGood

[Arthur Brown]

Generating 1000w will consume the same amount of engine power regardless of the nominal voltage (probably 1500 engine watts or 2BHP).

 

Getting serious power out of the alternator WILL need serious belt(s) either a well fitted polyVee or a matched set of plain vee belts. Hopefully the engine water pump is driven by a less taxed belt along maybe by the starter alternator

 

A "travel power" is simply an alternator providing DC to an inverter which controls the generator to make enough power regardless of RPM. -The inverter ensures that the power made by a vari speed engine has a constant and usable AC frequency.

Edited March 17, 2015 by Arthur Brown

[OldGoat]

Generating 1000w will consume the same amount of engine power regardless of the nominal voltage (probably 1500 engine watts or 2BHP).

 

Getting serious power out of the alternator WILL need serious belt(s) either a well fitted polyVee or a matched set of plain vee belts. Hopefully the engine water pump is driven by a less taxed belt along maybe by the starter alternator

 

A "travel power" is simply an alternator providing DC to an inverter which controls the generator to make enough power regardless of RPM. -The inverter ensures that the power made by a vari speed engine has a constant and usable AC frequency.

 

 

I agree, I just couldn't understand the initial argument EXCEPT there would be less losses in powering the washing machine via a travel power with it's more efficient inverter (?) than going down to 12V and up to 240V.

 

Twin row V- belts is NOT an option as there is no proper power take-off at the front of the shire engine - and integral spline and not a simple keyway is required for that amount of power.

[peterboat]

 

 

Why? Apart from possible efficiency differences. 746 watt = 1 hp so it does not matter if its 240 volts at 10 amps or 12V at 200 amps, it is still the same horse power.

 

What have I missed?

You have missed nothing Tony. The problem is that Barrus Shire should put a auto tensioner on the engine like cars have. If a Jaguar can run a large alternator and aircon of a multipoly V belt without slipping I am sure Barrus can too. I always laugh at the crap engineering I see on boat engines its 1930 s technology in the 21 st century

 

Peter