Why do people rev up petrol strimmers?

[Commander Kinsey]

Why do people rev up petrol strimmers? Surely the engine would prefer to be kept at a constant speed? The neighbours would certainly prefer it!

[Marilyn Manson]

Why do you rev up your petrol vehicles? Surely the engine would prefer to be kept at a constant speed.

[Marilyn Manson]

Why did you make your "constant speed" comment a question?

[alan_m]

Probably for the same reason you don't stay in tick-over when you attempt to move away in your car.

[Commander Kinsey]

You don't change it that often, only when you need to go a different speed. There's no need to slow down the strimmer for 1 second while you're not cutting.

[Commander Kinsey]

Because I'm inviting people to tell me why the engine wouldn't prefer it. Have you never heard something like "surely it's not going to rain today?" to which the response could be "yes it will, because the weather forecast you watched is s**te".

[Commander Kinsey]

But you don't stick it back in neutral for a second when you don't need power.

[Marilyn Manson]

Never. Why would people make a statement sound like a question?

Pop quiz: Where is this happening?

TODAY SUN 07/25 HIGH 51 °F70% Precip. / 0.04 in Showers this morning becoming a steady light rain during the afternoon hours. High 51F. Winds S at 10 to 20 mph. Chance of rain 70%.

[Marilyn Manson]

...or maintain a steady speed up or down a hill. Use cruise control...watch your revs... rarely rock solid depending on the terrain.

You didn't specify a time frame in your OP. It takes me more than 1 second to walk from one cutting area to another.

[NY]

That applies to so many small petrol engines. Why not run the engine at a constant speed, which is so much less irritating that an engine which is constantly speeding up and slowing down. It's the same with scrambler bikes which rarely run at constant engine speed for more than a second at a time.

A larger, lower-speed engine would help so it had the torque to do the job without screaming at 10-20 thousand RPM.

I wonder how long fast-revving two-stroke engines, with the vile-smelling exhaust, will remain legal. When we bought a petrol mower, we got a four-stroke one that runs at a lower speed and doesn't kick out oily blue smoke. Sadly petrol was the only option, because we have a very large garden so a) a battery would not last very long in a battery-electric mower before needing to be charged for several hours before the next bit of the lawn could be cut, and b) I'd need a couple of hundred metres of extension cable for a mains-electric mower.

[Ed Pawlowski]

Has nothing to do with the mechanics of the engine running. Has everything to do with the sound. Guys just like vrooom vrooooom.

[Tim+]

Did you look at robotic mowers? My sister has one. Very quiet any will work away unattended, charging itself when needed. By necessity it has to be a mulching mower which may not suit you.

Tim

[NY]

Funny you should say that. We did look at robotic mowers and it's still an option if I get fed up of mowing the lawn. Most of our neighbours with similar size gardens have ride-on mowers, but they leave the lawn looking very patchy and they often still need a push mower for all the fiddly bits - and our garden has a *lot* of fiddly bits.

When I used to mulch the grass (ie let it come out of the back of the mower onto the lawn), I could do the whole lawn in a few hours. Now I collect the grass and take it to the tip, it takes longer because of all the times I have to stop and empty the grass box into the rubbish sack, and then take the sack up to the car and bring the next one down. But I still keep at it. A ride-on would be fun but expensive. A robotic mower would be great fun to watch. I presume it would have to run continuously to avoid the Forth Bridge problem - ie you need to start at the beginning again as soon as (or even before!) you've finished, to keep the grass short.

There is also the problem that the only places where the robot's "charging home" could be situated, with an electricity supply, are the wrong side of the gravel drive which I imagine the mower could not run across. Certainly the push mower and the wheelbarrow get bogged down in the damn gravel - it was there when we bought the house...

[JNugent]

I'll go with that. I like the sound of a crosscut shredder when I put correspondence through it.

[rbowman]

That has a lot to do with it but two-stroke engines are notorious for fouling their plugs at idle. The classic Harley engine also isn't great at idle. It's a wasted spark design with both cylinders firing together with one cylinder on the compression stroke and one on the exhaust stroke. At idle speeds the cylinders aren't scavenged efficiently and the engine is misfiring about 10% of the time. Modern FI engines adjust better but back in the day engines with hot cams and 4 barrel carbs also were very rough at idle.

[Jim Joyce]

Battery technology, specifically run time and charge time, has improved in recent years. My neighbor's riding mower has a dual battery setup that's advertised to run for about 90 minutes on the batteries that it came with, but you can either get a second set of batteries and swap them out mid-job, or get a set with higher capacity. When she mows, she's done with the rider in less than 45 minutes so she never runs into the charge limit.

Then she switches over to her battery powered push mower to finish what the rider was unable to reach. There, too, the single battery provides more run time than she needs.

Next, she switches over to her battery powered string trimmer, which would run way longer than she needs it to.

Finally, she grabs the battery-powered leaf blower to blow off the driveway and sidewalks.

[Ralph Mowery]

I think that is some parts of the US the 2 stroke engines for most lawn equipment are illegal to sell now. I know on some lakes the engines that put out polution are not allowed.

I hate the slow running engines. They are mainly that way in the US due to the safety factor that someone decided on. The blade speed can not be but so fast for the home owners. They do not mow with a crap. I think the professional mowers do not follow the same rules.

[Ralph Mowery]

I won't even think about battery powered devices for replacing gas engines unless the company is a big one and guarentees the battery for as long as you own the equipment.

I have had to throw away many battery powered hand tools because of the battery. Many times you can get an updated drill with 2 new batteries and charger for the cost of just the batteries. Then those batteries are not compatiable with the older drill. Too bad there are no standards for the rechargable power packs where one pack will fit in several companies tools. Like a standard 9 volt battery will fit in hundreds of devices. Or the AA,AAA, C and D cells fit many devices.

[Roger Mills]

Let's assume for a moment that it's a serious question - though I doubt it!

The connection between the engine and the working end is via a centrifugal clutch. At idling speed, the cutters don't rotate. Only when you rev the engine does the clutch engage and allow the thing to cut.

I suspect that you knew that all along!

[Jim Joyce]

If you're going to make that one of your personal requirements, then I agree, you won't be using battery powered tools anytime soon. I don't think most people would have that kind of rule, though. I certainly don't. I use the heck out of my cordless tools, to the point where I've dropped off their corded equivalents at Habitat ReStore so someone else can have them.

Most of the name brands make an effort to keep their batteries compatible across their tool lines and across a long period of years. My Bosch and Dewalt cordless tools are still on their original batteries after 7-8 years of home project use, but both of those companies still use compatible batteries on their current products. My neighbor uses all Ryobi, which I'm not fond of as a tool brand, but there too, Ryobi has been making batteries for years that remain compatible with their older stuff.

I get your point, though. Brand X batteries aren't compatible with Brand Y tools or Brand Z tools or anything other than Brand X, and vice versa. You'll see people doing Frankenstein hacks on Youtube to make them work, but that's not a task for the mainstream.