Further to our recent discussion, I checked out eight different mowers
at Payless today. All had geared reduction drives plus some form of
soft coupling between the motor and blades. The only exception was a
non-grass collecting Flymow which was direct coupled, ie cutter on
motor shaft.
The grass collecting Flymows had gearoxes (or it may have been a
toothed belt). A speed reduction device anyway.
I was getting funny looks, I couldn't dismantle them of course.
So, as I suspected, the Naturist Philosopher was right.

In article ,
harry writes:
Further to our recent discussion, I checked out eight different mowers
at Payless today. All had geared reduction drives plus some form of
soft coupling between the motor and blades. The only exception was a
non-grass collecting Flymow which was direct coupled, ie cutter on
motor shaft.
The grass collecting Flymows had gearoxes (or it may have been a
toothed belt). A speed reduction device anyway.
I was getting funny looks, I couldn't dismantle them of course.
So, as I suspected, the Naturist Philosopher was right.

I don't know what thread you're looking at.

Universal motors (i.e. with brushes) have to be geared down
to driver mower blades - they spin too fast otherwise.
Universal motors are used in cheaper low grade mowers of the
type you'll find in the sheds. Universal motors are dirt cheap
but are completely wrong torque profile for grass cutting,
which is why they slow down under load just when you need more
cutting power, and deliver much less.

Induction motors drive mower blades directly.
You'll find these on higher spec mowers, but you may have to
go to a mower specialist. The torque profile of an induction
motor is much more ideal for grass cutting - max torque at
nearly full speed (so it will maintain speed and cutting
power under load), rather than at locked rotor. Expect to pay
more, but also expect longer motor life. Also, the induction
motor is significantly more efficient, and unlike the cheap
universal mower motors, IME induction motors in mowers don't
waste power heating themselves up way too hot to touch. As a
result of this, don't be surprised to find they are lower power
rating for same width cut, because they manage to use more
of the power for cutting and less wasted in the motor.
No motor brushes to wear out either.

--
Andrew Gabriel
[email address is not usable -- followup in the newsgroup]

On 19 Aug, 18:37, (Andrew Gabriel) wrote:
In article ,
* * * * harry writes:

Further to our recent discussion, I checked out eight different mowers
at Payless today. *All had geared reduction drives plus some form of
soft coupling between the motor and blades. The only exception was a
non-grass collecting Flymow which was direct coupled, ie cutter on
motor shaft.
* The grass collecting Flymows had gearoxes (or it may have been a
toothed belt). A speed reduction device anyway.
*I was getting funny looks, I couldn't dismantle them of course.
So, as I suspected, the Naturist Philosopher was right.

I don't know what thread you're looking at.

Universal motors (i.e. with brushes) have to be geared down
to driver mower blades - they spin too fast otherwise.
Universal motors are used in cheaper low grade mowers of the
type you'll find in the sheds. Universal motors are dirt cheap
but are completely wrong torque profile for grass cutting,
which is why they slow down under load just when you need more
cutting power, and deliver much less.

Induction motors drive mower blades directly.
You'll find these on higher spec mowers, but you may have to
go to a mower specialist. The torque profile of an induction
motor is much more ideal for grass cutting - max torque at
nearly full speed (so it will maintain speed and cutting
power under load), rather than at locked rotor. Expect to pay
more, but also expect longer motor life. Also, the induction
motor is significantly more efficient, and unlike the cheap
universal mower motors, IME induction motors in mowers don't
waste power heating themselves up way too hot to touch. As a
result of this, don't be surprised to find they are lower power
rating for same width cut, because they manage to use more
of the power for cutting and less wasted in the motor.
No motor brushes to wear out either.

--
Andrew Gabriel
[email address is not usable -- followup in the newsgroup]

There was a previous debate where a couple of clowns were insisting
there was no gearbox on electric rotary mowers.
http://groups.google.co.uk/group/uk.d-i-y/browse_thread/thread/366836481fb76305#

I have never had one but I was of the opinion that a gearbox/toothed
belt would be needed.
I went and had a look and it was the case, they do have a gearbox.
An induction motor would be heavier and the have a poor starting torque

harry wrote:
On 19 Aug, 18:37, (Andrew Gabriel) wrote:
In article ,
harry writes:

Further to our recent discussion, I checked out eight different mowers
at Payless today. All had geared reduction drives plus some form of
soft coupling between the motor and blades. The only exception was a
non-grass collecting Flymow which was direct coupled, ie cutter on
motor shaft.
The grass collecting Flymows had gearoxes (or it may have been a
toothed belt). A speed reduction device anyway.
I was getting funny looks, I couldn't dismantle them of course.
So, as I suspected, the Naturist Philosopher was right.
I don't know what thread you're looking at.

Universal motors (i.e. with brushes) have to be geared down
to driver mower blades - they spin too fast otherwise.
Universal motors are used in cheaper low grade mowers of the
type you'll find in the sheds. Universal motors are dirt cheap
but are completely wrong torque profile for grass cutting,
which is why they slow down under load just when you need more
cutting power, and deliver much less.

Induction motors drive mower blades directly.
You'll find these on higher spec mowers, but you may have to
go to a mower specialist. The torque profile of an induction
motor is much more ideal for grass cutting - max torque at
nearly full speed (so it will maintain speed and cutting
power under load), rather than at locked rotor. Expect to pay
more, but also expect longer motor life. Also, the induction
motor is significantly more efficient, and unlike the cheap
universal mower motors, IME induction motors in mowers don't
waste power heating themselves up way too hot to touch. As a
result of this, don't be surprised to find they are lower power
rating for same width cut, because they manage to use more
of the power for cutting and less wasted in the motor.
No motor brushes to wear out either.

--
Andrew Gabriel
[email address is not usable -- followup in the newsgroup]

There was a previous debate where a couple of clowns were insisting
there was no gearbox on electric rotary mowers.
http://groups.google.co.uk/group/uk.d-i-y/browse_thread/thread/366836481fb76305#

I have never had one but I was of the opinion that a gearbox/toothed
belt would be needed.
I went and had a look and it was the case, they do have a gearbox.
An induction motor would be heavier and the have a poor starting torque

mutatis mutandis, the power you can get from an electric motor is the
function of the size of the ironwork, times the RPM. That is torque is
almost completely a function of the iron mass.

So small motors need to rev to get the power, and be geared to get teh
torque.

Universal motors develop constant torque for a given current across the
rev band. Great starters.

Induction motors are one speed motors, have no more torque, and a lot
less at low RPM.

Its not really a good idea to compare apples with oranges. a typical
1500 watt motor that is in a washing machine weighs in about 20lb. I can
find you one that will do the same power for under 1lb weight, albeit
with permanent magnets and at 6-10k RPM.

We were somewhere around Barstow, on the edge of the desert, when the
drugs began to take hold. I remember harry saying
something like:

There was a previous debate where a couple of clowns were insisting
there was no gearbox on electric rotary mowers.
http://groups.google.co.uk/group/uk....836481fb76305#

You really are full of it. The discussion was about some gearing in some
lawnmowers. Not all lawnmower motors are geared, contrary to what TNP
was insisting in his usual dogmatic fashion.

Grimly Curmudgeon wrote:
We were somewhere around Barstow, on the edge of the desert, when the
drugs began to take hold. I remember harry saying
something like:

There was a previous debate where a couple of clowns were insisting
there was no gearbox on electric rotary mowers.
http://groups.google.co.uk/group/uk....836481fb76305#

You really are full of it. The discussion was about some gearing in some
lawnmowers. Not all lawnmower motors are geared, contrary to what TNP
was insisting in his usual dogmatic fashion.

Well if not they will have to have a massive multipole motor, especially
if its induction.

Which is a waste of iron and copper.

On 19 Aug, 20:34, Grimly Curmudgeon
wrote:
We were somewhere around Barstow, on the edge of the desert, when the
drugs began to take hold. I remember harry saying
something like:

There was a previous debate *where a couple of clowns were insisting
there was no gearbox on electric rotary mowers.
http://groups.google.co.uk/group/uk..../thread/366836...

You really are full of it. The discussion was about some gearing in some
lawnmowers. Not all lawnmower motors are geared, contrary to what TNP
was insisting in his usual dogmatic fashion.

In my sample 7 out of 8 were. The one that wasn't was a unique type.
So I imagine it's the only one that has no gearbox. Or belt.
They are geared for the reasons above. All perfectly logical.

"harry" wrote in message
...
On 19 Aug, 20:34, Grimly Curmudgeon
wrote:
We were somewhere around Barstow, on the edge of the desert, when the
drugs began to take hold. I remember harry saying
something like:

There was a previous debate where a couple of clowns were insisting
there was no gearbox on electric rotary mowers.
http://groups.google.co.uk/group/uk..../thread/366836...

You really are full of it. The discussion was about some gearing in some
lawnmowers. Not all lawnmower motors are geared, contrary to what TNP
was insisting in his usual dogmatic fashion.

In my sample 7 out of 8 were. The one that wasn't was a unique type.
So I imagine it's the only one that has no gearbox. Or belt.
They are geared for the reasons above. All perfectly logical.


I have only had Flymos and these did not have any reduction in the drive.

In article iasbo.27331$UD.134@hurricane,
"John" writes:
"harry" wrote in message
...
On 19 Aug, 20:34, Grimly Curmudgeon
wrote:
We were somewhere around Barstow, on the edge of the desert, when the
drugs began to take hold. I remember harry saying
something like:

There was a previous debate where a couple of clowns were insisting
there was no gearbox on electric rotary mowers.
http://groups.google.co.uk/group/uk..../thread/366836...

You really are full of it. The discussion was about some gearing in some
lawnmowers. Not all lawnmower motors are geared, contrary to what TNP
was insisting in his usual dogmatic fashion.

I don't agree with much of what TNP said in his two articles
in this thread, but ICBA to go through and correct every point,
and I'd just be repeating what I already said.
I didn't read all of the other thread, but I was referring
to mains mowers here, not battery ones.

In my sample 7 out of 8 were. The one that wasn't was a unique type.

I would have guessed an even higher ratio overall, because most
people who buy electric, buy cheap universal motor mowers.

So I imagine it's the only one that has no gearbox. Or belt.
They are geared for the reasons above. All perfectly logical.


I have only had Flymos and these did not have any reduction in the drive.

I've repaired a number of other peoples' flymos, and they have
all been geared, but admittedly cheap models. (Actually, they
often aren't repairable because the plastic brush mounting
melts when the brushes wear out - they seem to be designed as
disposable consumables, I guess so you go and buy another one.)

My own two mowers are induction - one almost 20 years old (now
with a relative), and the other is 10 years old.

--
Andrew Gabriel
[email address is not usable -- followup in the newsgroup]