I have checked my mowers engine running speed this week and my 21" Hayter (Briggs 190cc) is running at only 2600rpm and my 16" Izy (GCV160) is running at 3000rpm. When researching what they should be i came across this info .... Can anyone confirm if this info seems about right?? ... I will go for the higher figures if safe to do so.
ANSI B71.1-1964 and earlier standards:
For 18" blade: 4456 (4250) rpm max
19" blade: 4222 (4000) rpm max
20" blade: 4011 (3800) rpm max
21" blade: 3820 (3600) rpm max
22" blade: 3646 (3450) rpm max
ANSI B71.1-1968 standard and revisions thereafter:
For 18" blade: 4032 (3800) rpm max
19" blade: 3820 (3600) rpm max
20" blade: 3629 (3400) rpm max
21" blade: 3456 (3250) rpm max
22" blade: 3299 (3100) rpm max
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anyone?
I suspect thos figures are US based and reflect their EPA and safety rules.
There's quite a few LJN threads on this type topic.
I'd take a closer look at the UK engine manuals supplied with the machines and identify where peak torque and peak power are produced and look to start at the lower of those two, so somewhere between 3k-3.2k rpm, although they can often go to 3.6k and above but you'll increase virbration and fuel consumption & decrease engine life.
Speeds are often left or set lower ~2.6-3.0k on delivery here in the UK, but would never push it higher than the limit imposed by the country specic limits in the manuals. Engine speeds etc are also linked to blade types (and amount of lift) for noise and safety reasons (blade speed etc).
The thought of an inferior 'copy' blade disintergrating at 4k rpm if it hits a rock or drain cover is frigthening :(
thankyou Gary
ANSI is a US body . That seems to be a max speed allowed, not the engine speeds of your specific mowers themselves. I've never seen a pedestrian to have a speed anywhere near 4456.
3k max for both Paul
i know all manufaturers differ however the engine does not, most rpm speeds are set for 2 reasons and should ideally not be changed
1, rpm is set to the best point in the engines power curve, this means that if you increase the rpm then yes the blade will turn quicker BUT the machine will have less power so will slow in heavy material,
this will increase the over all engine load and will start to ware the engine far quicker, if the oil changes are not adjusted for this then the engine will fail
2, the machine's are normally designed (i speak for etesia only here) to work with the engine set to the specific rpm, changing this will then increase noise and vibration beyond book values and will then start to add ware to YOU and the rest of the machine beyond it original design.
thankyou Neal. thats very helpful