OutdoorKing Repair Forum Forums Restoring, Customising and Modifying Reel-Type Mowers Inline Centrifugal Clutch replacement

Hi Guys,

Not sure if this is the best place to ask this question, Can anybody recommend a inline Centrifugal Clutch replacement for my Scott Bonnar 45 series? I would like to convert the original clutch to a modern protea mower style.

Has anyone attempted this successfully?

Regards
Peter

Anyone?

Deejay? Grumpy?

Hi Peter,
I have never heard of anyone attempting that modification, as the Scotty clutch, carefully adjusted works fine...and is a good safety feature, as the cutter can be disengaged when removing/replacing the catcher. There are pros and cons of the centrifugal clutch, and obviously the SB engineers decided on the friction drive as the best solution at the time.

There are some English reel mowers that have used centrifugal clutches for a long time: it is not a new idea. There are both positive and negative aspects of using them.

The positive feature is that whenever the engine is at idle, the reel does not rotate - no operator-action is required. This sometimes offers a safety benefit, such as when somebody drops something or does something really dumb - which most of us do at least occasionally.

The negative features of a centrifugal clutch are also safety-related. First, if the engine speeds up without the operator intending it, the reel starts and runs. Second, if some minor mechanical glitch prevents the engine from slowing down or stopping, the operator cannot prevent the reel from running. A skilled operator will then pull off the spark plug lead, but not everyone has the knowledge or presence of mind in an emergency to do that.

I doubt that it is difficult to fit a centrifugal clutch if you want to do so. Remember though, you need one that operates at the right speed: above the Briggs' idle speed of 1,750 rpm, and below the lowest speed you would ever want to use for mowing, which is probably around 2,200 rpm. (The only other engine you would be likely to fit is a Honda GX120, which idles at 1,400 rpm.)

I notice that the 1973-74 range of Victa Imperials also used a centrifugal clutch here in Oz.

The Masport Olympic reel mower made by Steelfort N.Z used a centrifugal clutch running a Tecumseh and I think Briggs which worked well enough. Then they changed to a twin cork clutch set up. Before that the Masport Morrison reel mower also had a centrifugal clutch, which was identical to the Victa one mentioned by Darryl ( as far as I can recall ) I only remember seeing 14'' Victa"s with a 2 stroke on them.
You may be able to purchase the centrifugal parts from Masport and modify them to suit your Rover 45. But would it be worth all the effort? The only issue I have ever had with the 45 top clutch is them coming loose or going out of balance. They should of never got rid of the cast iron ones.

Hi Tim,
That is quite correct mate, the Victa Imperial range (1973-1974) was from 14" to 24" cutting widths, and was in fact a clone of the Morrison mower, which itself had its roots in the Ransomes Mk 7 machine.
Scott Bonnar (when owned briefly by the Challenge Corporation NZ) produced a clone of the Morrison as well, but without the centrifugal clutch....seen here:

All very incestuous!

Thanks all for your replies. Lots of pros and cons. I have noticed the new Protea mowers are using Centrifugal clutches on there reel mowers. I think the manual levelled clutch as designed By Scott Bonnar is a lot safer than the centrifugal clutch.

good discussion topic.

Hi SMB45,
Yes mate, this has been a good discussion topic. As this thread is now complete, I will now close it.