petrol lawn mower recommendations?

[Stephen]

Hello,

Every year I say I am going to get a new mower but never get round to it, but I feel the time has come!

I currently have a Bosch electric mower that I have had since 2001. It says it has an induction motor and I don't know if that's the problem. Are these the wrong type of motors for mowers? It means it is quieter than other mowers but it is always stalling.

The blade curves up at the end and is supposed to eject the cuttings into a box but this never works. I thought it was because the grass was damp that it stuck together but even now when we have had all this sunshine, the mower clogs and the motor stalls.

Would a petrol mower be less likely to stall or clog? I've never had one before. I like the freedom of not having any wires.

I have a front garden that does not have a lawn yet but I'm not sure what else to do with it so it may get turfed! It is roughly 10'6" x

14'8" or 3.2m x 4.5m

The main use however would be for the back garden 18' x 41' or 5.5m x

12m approx. Though I will probably put raised beds, greenhouse, etc onto some of this in the future.

I know Honda is well thought of for small petrol engines. I see they do two "Izy" models: one is 16" and the other 18". From what I can tell, they use the same engine. I was looking at ones that propelled themselves to make it easier for me. It looks as though they only have one speed: is that an issue? The larger mower is slightly slower but I'm guessing that is because it weighs slightly more.

The larger mower costs £100 more. Is it really worth it for an extra two inches? If I have done my sums right, for my garden I would have to go up it 13 times with the 16" and 12 times with the 18", so it wouldn't save me much time. Perhaps I should save money and buy the smaller model? Either one is wider than my current electric one.

Thanks, Stephen.

[Tim Watts]

I know you said petrol, but I have one of the Bosch 36V Rotak mowers (about 3 years old now) and I've been very impressed. It does collect the grass extremely well and is surprisingly powerful.

The main thing is you need 2 batteries really, so you can swap back and forth for a larger lawn.

It replaced a petrol Hayter of similar cut width and it's lighter, no mains cord, and not bothered about side slopes (was always upsetting the Hayter doing those).

[Harry Bloomfield]

Stephen used his keyboard to write :

Unless the grass is very dried out, they all do clog up. I have a tractor/mower, which uses a duct from the cutting deck, to a massive collector bag hooked onto the rear. That clogs up to the point where I gave up on collecting it because the duct would choke up so very often. I just mulch it back onto the soil now and carry a stick to poke the duct clear when it chokes. Process is cut, then go around a second time to mulch it, it takes 30 minutes to fly round, once I have gained control of it after the winter and it has dried out enough to drive upon.

[PeterC]

My Honda Izzy does tend to clog if the grass is damp and the cut is more than an inch or two off. I got the 16" because, as you say, it has the same motor and thus it should be less stressed. My gardens are a bit bumpy and have lots of things to get around, so the smaller one - and definitely not SP (I could see that it would take me along, with so any corners and curves) - seemed to be better. Now, when I used to cut the grass next door, I've had to 3 cuts at times. It is sports-pitch grass and grows fast an thick. The Honda would need 2 cuts if the grass was 4 - 5" long. The new neighbour bougt an electric mower form B&Q - a cheap Mac Allister IIRC, about £70. I wished him luck with that! I was right PO'd when it cut the grass with no trouble at all - it was about a quarter of the price of the Izzy. Only snag is the flex, especially round shrubs etc.

[The Natural Philosopher]

[David]

We have a Bosch Rotak and it seems to be fine, although we currently only have a small lawn. I don't know if you just had a bad example.

Best mower we have had was a Harry (no longer made) which had an alloy deck and a Briggs & Stratton engine. Generally abused and ignored and it always seemed to start and cut well.

I have found the electric mower to be much easier than petrol, though.

Cheers

Dave R

[Martin Brown]

Odd. I have used both sorts and never had an electric one stall on me.

How strange. the air flow should be sufficient to blow stuff into the bag or whatever collection method it uses. Have you tried cleaning the bag that the grass cuttings go into? If air can't get out then there will not be enough air flow to carry the grass cuttings along.

Mine is a Mountfield 18" petrol with 135cc Honda engine. It is my second in three decades used to cut about 1/3 acre all summer long. Its predecessor fell apart after 20 years due to petrol spills and general wear and tear. It has only stalled on me when I tried to cut a flagstone or edging with it and even then it sometimes cut a piece off.

That is probably a bit small to be worth the effort of a petrol mower. You should be able to get an electric one that works OK.

The 18" is my choice for a moderately large set of lawns with one of them on a fairly aggressive slope where the self propelled feature is helpful. On the flat I don't find it all that important. YMMV

It only has one speed - sort of slow walking.

I think it depends a lot on how you get on with things mechanical. They are fairly simple engines and quite easy to maintain and service but if you are having to pay someone to do that work they can become expensive.

Electric is by comparison plug and play. Try giving the grass box on your existing one a really good spring clean and you may be surprising at how much performance improves. Something is wrong if it jams.

[Andrew]

Are you sure. He insists on popping up here all the time.

[Harry Bloomfield]

Martin Brown was thinking very hard :

Every mower, electric hover (the early orange hover machine), rotary engined and even the current tractor and its immediate predecessor have suffered stalls. More so in the first cuts of the season, but better as the weather warmed up and the grass became drier. I had to be ready to lift the hover off the grass, when I heard it labouring too much.

All those which collected grass, have suffered frequent choking with cuttings too. Today the grass was warm and it was fairly dry - using a

14HHP tractor/mower as usual without any grass collection, it managed to choke up it's duct around 5 times, to the point where I had to stop and poke the duct clear with a stick. I have tried running without the duct, but that blows the cuttings onto the drive pulleys and eventually jams the drive system at the back axle/ diff.

[David]

I'm going to look at this from a very different angle. I suspect you don't cut your grass often enough so you are cutting longer grass. One of the best lawns I knew was from an elderly chap who used a push mower without a box to cut his grass. He did it every day without fail, even if it was raining, as there was only a little growth he could just walk the mower, no going back and forth to get it through the grass. If you cut a couple of times a week or even more then you would find it much easier and as you would be taking off a lot less grass every time it would be an easy walk for both you and your mower. Also have a look at the underside, is it clean or has it got grass built up there which will imped the flow of air and clippings. You are only cutting a small area and will be walking (if you cut a 12" strip each time) less than 300 yds, so doing that 2 or 3 times a week will only take you minutes each time and as the grass will be shorter then you wont have to empty the box often, and you will end up with a much better lawn.

[Harry Bloomfield]

David pretended :

It is usually cut around twice per week, on two consecutive days. It is far too uneven and large to even contemplate a push mower, or really anything less than a tractor. I went through a series of different mower types, before arriving at a tractor. All the others simply couldn't cope with the size of the job, it would take forever and none survived very long. The tractor whips round so quickly, it actually does the job with less fuel than other types I have tried. It is also much easier on me, just driving it around.

When I first moved here, the garden was buried under bramble. I tried electric hover, petrol hover, petrol cylinder, electric cylinder - the size and the time needed beat them all.

[Martin Brown]

If you wait until the grass is ridiculously long before cutting it or try to cut it when it is far too wet then yes you probably can.

Something doesn't sound right. I sometimes have to free the grass exit if I try to cut one more stripe than I should have done but you can hear the tone of the motor change and see bits of grass dropping out the back when the collection chamber is nearly full. I tend to push it a bit close since I prefer to be at the end nearest the heap when I stop.

I blame lack of mechanical sympathy for your woes.

[Harry Bloomfield]

Or it could just be very tough grass and never throughly dries out. We have a few inches of soil, under which is very heavy clay. It used to flood in heavy rain, but I put in lots of drainage to try to help prevent it. It usually needs a week of dry warm weather, even in the summer, before it is fit to try to cut it - so sometimes it just has to be left uncut. The first cut of 2018 was very delayed by the wet weather.

[Andrew Gabriel]

Induction motor is the right type for an electric mower, but is only found in more expensive models. If yours is stalling, it's overloaded or there's something wrong with it. Note it won't have much starting torque, so it won't be able to start if clogged, but once running, it has high torque at nearly full speed, so it shouldn't slow much under normal load. The only failure mode unique to induction motor mowers is the capacitor failing and they cost just a few quid to replace. Symptom is that the already low starting torque gets even lower or drops to nothing in the case of complete failure (can be spin started if you don't mind losing all your fingers!!!), but once started it runs normally.

A universal motor used in most electric mowers is exactly the opposite way around - lots of starting torque, but it can't maintain speed when cutting, since a universal motor has to be slowed much more under load to generate torque. Also a universal motor spins way too fast, so it needs additional pulleys and belts to run the blade at the right speed for mowing. This is a lot more to fail - motor brushes, and the belt drive have limited life. Generally, the build quality is way lower than induction motor mowers and the efficiency lower, so needs a higher power rating for same width cut (and motor runs much hotter, which also doesn't help the longevity).

[The Natural Philosopher]

This is all utter codswallop.

A properly designed and near 'perfect' motor will genee maximum torque one RPM below 'free runnimng'

The theory is simple. The motor will spin till the back EMF - a product of the speed, number of turns on the armature and magentic field - matches the applied EMF.

When a load is applied if the motor drops speed, the current will incerase until the speed is retired, less any copper losses.

That is the EMF and RPM always matches the applied voltage minus IR losses in the copper..

On good motor this can result in near instant burnout when stalled.

What I suspect you have encountered is 'stall proof' motors that deliberetely have far top much resistance in the windings.

Induction motors are crap really for serious power. Obnce they lose synchronism, they are useless.

[Graeme]

In message , Stephen writes

I bought a Honda 'Easy Start' 4 stroke petrol mower a few years ago, and it has been wonderful. Starts first or second pull every time, cuts well and is light enough for wife to use easily as well. Self propelled at walking pace (single speed) and has never clogged. Highly recommended.

[Harry Bloomfield]

It happens that The Natural Philosopher formulated :

They are at their best for driving low inertia loads, where the loading gradually increases as the speed increases.

[dennis]

That must be why they use them for virtually all large industrial machines because they are cr@p!

[Harry Bloomfield]

on 01/06/2018, dennis@home supposed :

In industry, they have several clever starting methods to overcome the drawbacks of induction motors, so for industry they make for a very reliable, cheap and simple to build motor. Universal motors just don't scale up so easily or cheaply, nor as efficiently.

[fred]

We had a Westwood mower that collected the cutting effortlessly thanks to t he driven brush at the rear. Our trouble was getting rid of all the grass s o we switched to a Husqvarna mulching mower but to be effective the grass r eally needs cut twice a week otherwise the mulching isn't so effective.