Half crank or Full crank trimmer?

rollerzeke(z5)May 19, 2007

Hello all.

When purchasing a medium to heavy use string trimmer is it important to consider the "half crank or full crank" terminology? Are these terms related to engine internal design or the starting system?

Thanks for any advice.

Good day.

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I think it refers to having a bearing at both ends of the crankshaft rather than just one. This would imply a more durable and heavy duty design with full crank.

    Bookmark   May 19, 2007 at 3:04PM
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nevada_walrus(Boulder City)

You simply will not find a half crank that fits into the medium to heavy duty class. Half cranks are generally considered cheap throw aways. That's not to say they don't have a place in the market, they certainly do. Many home users on a tight budget find these to be a good fit. But they will never be considered a quality unit.

    Bookmark   May 19, 2007 at 5:28PM
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Hello all.

Thanks for the info fordtech and nevada walrus. I've got my thinking cap on straight now.

Good day

    Bookmark   May 19, 2007 at 6:04PM
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mattv21(z9 Houston)

Right, and it ultimately affects not the internal design but also the starter setup. Because a "half-crank" only has that single crankcase exit, you'll find the starter for it buried in the drive shaft's PTO side. That makes it virtually a complete disassembly just to replace the recoil starter. Ergo, it's throw-away if you break the cord or otherwise screw up the starter. On all full-shaft models, you'll find the starter on the back of the engine, the opposite of the shaft PTO. Replacing the recoil unit on these is basically just a four-screws process. So the visual giveaway to whether a trimmer is "full" or "half" shaft is the location of the starter.

    Bookmark   May 21, 2007 at 2:48PM
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Hello all.

Home run mattv21!
Thanks for that information.

Good day.

    Bookmark   May 21, 2007 at 3:55PM
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Had a half-crank Troy Bilt for 3 years, replaced it today with a full-crank Echo. Extra heft in the crankshaft isn't the only thing they skimp out on. The Echo manual actually lists maintenance intervals, procedures and part numbers. The Troy Bilt's manual has none of those things because it's assumed it'll be on the curb before any maintenance is necessary.

    Bookmark   May 30, 2007 at 8:47PM
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I have two SRM2600 Echo that are getting quite old. They still run like new and I wouldnt trade them worn out for 4 brand new economy models. I dont think you can kill these bad boys.

    Bookmark   May 30, 2007 at 9:11PM
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I have both Echo and Shindaiwa full crank trimmers and a Ryan (Lawn-Boy) half crank unit. The full crank models are smoother, start easier, just better all the way around than the half crank unit. Echo and Shindaiwa are 300 hour rated engines, most half crank engines are rated 50 hours. The best value in a trimmer are the straight shaft Echo units bought from a service providing dealer IMHO.

    Bookmark   May 31, 2007 at 12:22PM
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I've had a 'half-crank' Ryobi 725r for 14 years with no problems in light homeowner use. It's the 'Click-Link' and I have the blower head, so it's my trimmer and blower. If anything happened to it I'd get another one if I could still find a new one. It doesn't have the 'dead-man' switch like the new ones that you have to hold down.

    Bookmark   May 31, 2007 at 5:26PM
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I havent looked at any new ones lately and was unaware of a deadman switch. It hurts the arthritis enough as it is to hold that thing at an angle for long periods of time without that hassle added in.

    Bookmark   May 31, 2007 at 7:48PM
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And how about that goofy extra chain brake on the new chainsaws? My neighbor got a new saw and asked me to fire it up for him. I didn't know about the brake you have to release, but got the engine started anyway. When smoke started coming up off the brake, I knew something was bad wrong! I guess it's a kickback brake.

    Bookmark   May 31, 2007 at 10:44PM
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IIRC the deadman switch he's talking about is just a grip safety, like a Colt pistol. It's so the throttle can't be goosed unless you're holding the trimmer. They're removable, by the way.

I usually won't go near low-end trimmers any more (especially Ryobis, I hate working on those) but I have to speak up for the older Homelite 25cc half-crank trimmers. They're _not_ commercial duty, but every one I've owned or worked on has been nails. I got my first one (used) out of a trash bin in 1998 or so, used it for a few different lawns for 8 years, and sold it to a guy who does 12 lawns a week and it's still runnning like new.

Of course now that I'm running a Stihl FS-74 I can't say I miss the Homelite.

    Bookmark   May 31, 2007 at 10:53PM
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