Vee belt problems

solarman216 · 28-07-2019, 21:45

Anyone on here expert on Vee belts, I am having problems with my air compressor, I think I know the problem but do not know how to cure it other than put an idler pulley on the slack side, so here it is, 12 HP 4 stroke motor driving a large horizontally opposed twin compressor, (do not know its CFM but it was made to drive a road drill with only the tubular frame as a receiver, petrol driven with twin belts, engine blew up (might have been twin but cannot remember, it was many years ago) so I grabbed it) so my motor being single cyl 4 stroke the power kick is high, couple that with the twin pulses from the compressor and you can begin to see why the slack side of the belts start to jump wildly near full load, just fitted a matched pair of Gates A belts but no better, if I continue to run it as is the belts will fail in no time, so you see the problem, maybe they make stronger non stretch belts but I have no idea, Rick

panelbeater · 29-07-2019, 08:28

i made my first compressor from a train shunting engine.
i had the twin vertical high out put pump in a frame i built and a 5ft high big round freestanding reciever next to it.
the 10hp 3phase motor mount next to pump on slider so belt ajustments could be made.
i put a pair of the biggest v thickness v belts on to the pullies that i machiened up,much bigger than what was on pump to start with.
this was run through a pressure switch so on/off was auto with a top pressure cut of with blow of valve.
this over enginered pully system worked as the ones pump came with could not cope with the big motor.
i did think about an ideler pully under spring tention but i did not need it.
the cfm was huge as it copped with apto 3 people drawing a lot of air all the time and it would still cut out.
so maybe a spring pully ideler might help or can you go much bigger on belt thickness.

macabethiel · 29-07-2019, 08:37

Just throwing this in - on some Mercs the alternator pulley has a spring type clutch mechanism - to reduce load on engine start up I assume.

Only know this as a friend B class kept on stalling just after start up when cold - not good on an automatic! Turned out the clutch mechanism in the pulley had seized.

Wallace · 29-07-2019, 12:24

Does the new setup use the same pulleys and belt sizes as the old one?

solarman216 · 29-07-2019, 20:49

Quote:

Originally Posted by Wallace

Does the new setup use the same pulleys and belt sizes as the old one?

The compressor pulley is original and not easy to change as it incorporates a fan, it is 185 mm diameter, (fan much bigger) the engine pulley is 125 mm, recently re grooved for the wider A belt, before it ran an alternator with narrower belts, dictated by the pulley on the alternator, current belt length 1650La I have the makings of a substantial idler pulley, cannot get the engine much closer as only few inches between them and space needed for maintenance, Rick

Wallace · 30-07-2019, 00:08

My thoughts are what differs from the original setup, pulley size and difference between driver and driven as that might change the contact area add slippage. As the drive pulley has been re-grooved, have you tried pulling the belts off and clocking the pulley whilst turning the motor over? Maybe try taking plug out with the belts as they are and checking run-out.

28-07-2019, 21:45	#1
solarman216 Off road maniac Join Date: Dec 2009 Location: Bexhill on Sea Vehicle: Y60 Patrol Me, 3 ltr Mrs Posts: 17,432	Vee belt problems Anyone on here expert on Vee belts, I am having problems with my air compressor, I think I know the problem but do not know how to cure it other than put an idler pulley on the slack side, so here it is, 12 HP 4 stroke motor driving a large horizontally opposed twin compressor, (do not know its CFM but it was made to drive a road drill with only the tubular frame as a receiver, petrol driven with twin belts, engine blew up (might have been twin but cannot remember, it was many years ago) so I grabbed it) so my motor being single cyl 4 stroke the power kick is high, couple that with the twin pulses from the compressor and you can begin to see why the slack side of the belts start to jump wildly near full load, just fitted a matched pair of Gates A belts but no better, if I continue to run it as is the belts will fail in no time, so you see the problem, maybe they make stronger non stretch belts but I have no idea, Rick __________________ Ex banger racer now off road maniac Lokka on the front with manual hubs Diff lock on rear 3 inch SS straight through exhaust Manly winch bumper with 13000 lb winch 10 spike ground anchor, with multiple straps and blocks Super strong body cills capped with scaffold pole 20% stronger springs all round aggressive off road tyres on wheels so just swap. Aim to get stuck and be completely self sufficient in extraction, love getting muddy, 2ft deep is good but rare.

29-07-2019, 08:37	#3
macabethiel Senior Member Join Date: Aug 2008 Location: Derby Vehicle: Freelander & Jeep GC 3.0 Posts: 4,416	Pulleys with built in clutch? Just throwing this in - on some Mercs the alternator pulley has a spring type clutch mechanism - to reduce load on engine start up I assume. Only know this as a friend B class kept on stalling just after start up when cold - not good on an automatic! Turned out the clutch mechanism in the pulley had seized.

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29-07-2019, 08:28	#2
panelbeater Senior Member Join Date: Dec 2012 Location: clacton on sea essex Vehicle: nissan terrano 2 2.7 tdi Posts: 1,640	i made my first compressor from a train shunting engine. i had the twin vertical high out put pump in a frame i built and a 5ft high big round freestanding reciever next to it. the 10hp 3phase motor mount next to pump on slider so belt ajustments could be made. i put a pair of the biggest v thickness v belts on to the pullies that i machiened up,much bigger than what was on pump to start with. this was run through a pressure switch so on/off was auto with a top pressure cut of with blow of valve. this over enginered pully system worked as the ones pump came with could not cope with the big motor. i did think about an ideler pully under spring tention but i did not need it. the cfm was huge as it copped with apto 3 people drawing a lot of air all the time and it would still cut out. so maybe a spring pully ideler might help or can you go much bigger on belt thickness.

29-07-2019, 12:24	#4
Wallace Senior Member Join Date: Aug 2018 Location: Middlesex Vehicle: '97 Terrano II 2.4 Xtreme Posts: 368	Does the new setup use the same pulleys and belt sizes as the old one?

30-07-2019, 00:08	#6
Wallace Senior Member Join Date: Aug 2018 Location: Middlesex Vehicle: '97 Terrano II 2.4 Xtreme Posts: 368	My thoughts are what differs from the original setup, pulley size and difference between driver and driven as that might change the contact area add slippage. As the drive pulley has been re-grooved, have you tried pulling the belts off and clocking the pulley whilst turning the motor over? Maybe try taking plug out with the belts as they are and checking run-out.