ihatepoundland Posted July 28, 2006 Share Posted July 28, 2006 Simple questions I hope; Who decided and when was it decided that 540/1000 would be good RPM speeds? And why these speeds? Quote Link to comment Share on other sites More sharing options...
MJB1 Posted July 28, 2006 Share Posted July 28, 2006 don't quote me on this rob, but i think these speeds are when the the engines working at it's optimum effiency , just like most car makers always put the best fuel results mesured at 56mph Quote Link to comment Share on other sites More sharing options...
ihatepoundland Posted July 28, 2006 Author Share Posted July 28, 2006 That makes sense and was my first thought, but just making sure I've got the basics right here....the pto remains at (e.g.) 540 no matter what rpm the engine is doing? Quote Link to comment Share on other sites More sharing options...
MJB1 Posted July 28, 2006 Share Posted July 28, 2006 the engine revs determine the speed at which the pto goes. when the engine works hard the pto speed will drop, depending where the maximum torque is for that particular engine , is where your 540 pto is geared to suit . the 540 speed on a 45hp tractor maybe at 2000rpm engine speed where as 540 on a 90hp tractor maybe at 2200rpm , this very much depends on where max torque is , a long stroke engine will hangin there for longer , thus retaining a consistant forward speed at the revs set & depending on how hard yer working it & it may well recover because it has a larger powerband , a short stroke engine will die quicker giving a smaller powerband to work with , the only way to recover this then is by changing down to a lower gear to keep the engine revs consistant Quote Link to comment Share on other sites More sharing options...
SMurF Posted July 28, 2006 Share Posted July 28, 2006 PTO is achieved at a rated engine rpm FORD 5610 1900rpm = 540pto MF fe35 1400rpm=540 on more modern tractors PTO speeds are set by a gear box and comes in ranges of 540,540economy,1000 540 economy is basicaly 1000 PTO speed reduced to 540 by means of engine rpm also there are different spline configurations between 540 and 1000 PTO Does this make any sence Quote Link to comment Share on other sites More sharing options...
MJB1 Posted July 28, 2006 Share Posted July 28, 2006 PTO is achieved at a rated engine rpm FORD 5610 1900rpm = 540pto MF fe35 1400rpm=540 on more modern tractors PTO speeds are set by a gear box and comes in ranges of 540,540economy,1000 540 economy is basicaly 1000 PTO speed reduced to 540 by means of engine rpm also there are different spline configurations between 540 and 1000 PTO Does this make any sence well it certainly makes a difference when yer pto shaft shears off when foraging :D :D my heads hurting now \ Quote Link to comment Share on other sites More sharing options...
ihatepoundland Posted July 28, 2006 Author Share Posted July 28, 2006 Cheers chaps, got it now Quote Link to comment Share on other sites More sharing options...
NIGEL FORD Posted July 28, 2006 Share Posted July 28, 2006 Cheers chaps, got it now But your original question still hasn't been answered as to who decided that machines should be operated at 540/1000/750 etc as a general industry standard. Was it set by the Nebraska testing station in America when they were monitoring power outputs of all the tractor makes from the early days before tractors were fitted with PTOs as standard.? I believe it may have been. Then there was the standardisation of the shaft stubs... some of the early tractors had smaller diameter shafts with 6 spline fitting than the current spec ones. Quote Link to comment Share on other sites More sharing options...
ihatepoundland Posted July 28, 2006 Author Share Posted July 28, 2006 Thanks Nigel, meant "got it" in relation to the second question I'm slightly confused as to why (and I hope I'm not asking something that has already been answered) why for example the figure of 540 was arrived? If I have understood so far, the rpm of the pto at the optimum engine rpm could have in theory have been geared for anything? Quote Link to comment Share on other sites More sharing options...
MJB1 Posted July 29, 2006 Share Posted July 29, 2006 ah got you , as in even with optimum engine performance, why wasn't the standard pto speed geared to 500 or 600rpm. Hmmmm, best ask MF Fan when he gets back from college next year , if he doesn't know then , at least we'll have another excuse to wind him up :D Quote Link to comment Share on other sites More sharing options...
ihatepoundland Posted July 29, 2006 Author Share Posted July 29, 2006 yep, thats the question (once I'd correctly established how a pto actually works ) My only idea is that it is a divisable of the average optimum engine torque those testers found? Quote Link to comment Share on other sites More sharing options...
allis8550 Posted July 29, 2006 Share Posted July 29, 2006 I believe the first manufacturer to fit a PTO was IH way back in the 20' or30's and the speed of 540 rpm was just an arbitary decision, but once people started to make implements to suit, other manufacturers were obliged to go with the same standard.The need for a faster speed in order to transmit higher power led to 1000rpm as a more logical speed.[ But what about some European tractors fitted with 4 speed pto's ?] Quote Link to comment Share on other sites More sharing options...
ihatepoundland Posted July 29, 2006 Author Share Posted July 29, 2006 Suits the implement? i.e no point stepping down the speed if the implement needs it stepped up? When you say "transmit higher power" could you explain...how does speed relate to power ? A reduction in speed by gearing just increases the torque but the only power lost is through friction...so surely all engine power (minus friction loses) could in theory be transmitted at 1 rpm? Quote Link to comment Share on other sites More sharing options...
Pingu Posted July 29, 2006 Share Posted July 29, 2006 ah got you , as in even with optimum engine performance, why wasn't the standard pto speed geared to 500 or 600rpm. Hmmmm, best ask MF Fan when he gets back from college next year , if he doesn't know then , at least we'll have another excuse to wind him up :D I'll ask on my first day just a 5 week wait But i was always told and led to believe the ptos were set at 540 and 1000 was because thatsthe speeds the pto's on the earlyier tractors were most efficent so ift became standardised on implements so that implements could be used on all different machines at the same speed Quote Link to comment Share on other sites More sharing options...
Deeredriver Posted July 31, 2006 Share Posted July 31, 2006 well guys over the weekend i emailed the nebraska tractor testing laboratory in lincoln nebraska asking your question this might be a bit strange for somebody to ask but i will give it a shot anyway a few of us guys have been wondering what brought about the pto speeds why was 540 the number chosen speed for running machinery at? also why was the figure 1000 chosen this is the actual reply I wouldn't have a clue. so the question still goes on nick Quote Link to comment Share on other sites More sharing options...
ihatepoundland Posted July 31, 2006 Author Share Posted July 31, 2006 Haha, well good on you for trying, think you may have got someone PA Quote Link to comment Share on other sites More sharing options...
JC Posted July 31, 2006 Share Posted July 31, 2006 well guys over the weekend i emailed the nebraska tractor testing laboratory in lincoln nebraska asking your question this might be a bit strange for somebody to ask but i will give it a shot anyway a few of us guys have been wondering what brought about the pto speeds why was 540 the number chosen speed for running machinery at? also why was the figure 1000 chosen this is the actual reply I wouldn't have a clue. so the question still goes on nick Classic!! Ideal political candidate reply!! :D :D Quote Link to comment Share on other sites More sharing options...
Deeredriver Posted July 31, 2006 Share Posted July 31, 2006 yea i didnt know it was in lincoln nebraska at a unveristy thats not that for from where i live heres website http://tractortestlab.unl.edu/ nick Quote Link to comment Share on other sites More sharing options...
Mac Posted August 1, 2006 Share Posted August 1, 2006 Before the pto was introduced belt driven equipments were common. The standard belt speed was 3100 ft/min. Thus I would guess the pto speed was originally choosen to provide some compatability with belt driven equipment. Prior to 1958 the standard pto speed was 536 rpm. In 1958 this was raised to 540 and a second standard ie 1000 rpm was introduced for high hp tractors. Quote Link to comment Share on other sites More sharing options...
ihatepoundland Posted August 1, 2006 Author Share Posted August 1, 2006 That sounds like a very good explanation I'm not going to ask why 3100 ft/min Quote Link to comment Share on other sites More sharing options...
Mac Posted August 2, 2006 Share Posted August 2, 2006 I am glad you are not asking because I would think one would need to look back at stream driven equipment to find the answer. Quote Link to comment Share on other sites More sharing options...
nashmach Posted August 2, 2006 Share Posted August 2, 2006 And it would depend on the size of the wheel which the belt is attached to as well me thinks Quote Link to comment Share on other sites More sharing options...
Eurodeere Posted August 2, 2006 Share Posted August 2, 2006 Torque is related to Power and speed, Power remains the same so if the speed is increased the torque is reduced. Hence a shaft of similar size can transmit more power if the speed is higher and hence torque lower. Good example is high revving bike engine, lots of power, no torque but low revving deisel engine, lots of torque yet both engines have the same power. Quote Link to comment Share on other sites More sharing options...
Tellarian Posted August 2, 2006 Share Posted August 2, 2006 As always, learn your history!! The first practical, mass produced PTO came with the Farmall 'heavy' of 1923/24, the PTO was mere an extension of the main crankshaft with a dog clutch. The engine, Wakusha petrol, ran at 535 - 540 RPM at normal / max speed. this then became the standard. http://www.agmuseum.com/1928_mccormick_deering_farmall_w.htm Later, after WWII, more power was required to be transmitted and multi cylinder diesels went to higher RPM, and alternate spec PTO was agreed at 1000 rpm as at 540 RPM insufficient power could be safely transmitted with existing PTO eqipment, shafts, UJs etc. PTO and spline arrangments were also standardised. Perhaps a current Mech Ag student will have the latest that can be put down a 1 7/8'' spline in terms of PTO output!! 3100ft - this was a safe belt speed for the technology and materials of the steam age. Steam flywheels are cast iron, good in compression but poor in tensile stresses. If certrain radial speeds were exceeded, flywheels would (and have) simply throw themselves apart, with predictable and often fatal consequences. http://www.rustyiron.com/engines/flywheel/ Quote Link to comment Share on other sites More sharing options...
Tractorman810 Posted August 2, 2006 Share Posted August 2, 2006 "As always, learn your history!!" my history teacher said that to me ,right before i drop that subject :D you wern't a teacher were you tellerain? Quote Link to comment Share on other sites More sharing options...
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