my 4 mowers, and mower deck repair

I have 4 mowers.  I use a scythe (21″ blade)  to clear the growth under  fruit trees for which it is ideal.  Extend the blade to the near side of the trunk and pull sharply toward you and the weeds are leveled, all while standing a distance away without worries of snagging branches or snakes (I refer to the venomous ones – copperheads or occasional rattler).  It is also useful on a hillside where riding a mower is iffy. For how I peen my scythe and hand sickle, search “peen” on this site.

scythe
scythe good for clearing fields, if you are up to it, otherwise handy for difficult to access spots

Next up is my 21″ push mower, basic model purchased new this year from a big DIY store.  Note the large rear wheels for rough ground.  I use it for cutting and mulching the walkways between the raised beds.  It has a sophisticated Briggs Stratton motor which does not require use of a choke and starts (so far) on first pull.

handy gas powered push mower
handy gas powered push mower

The biggest mower is the Bush Hog, which is 5 ft wide and shown here attached to my tractor.  I bought it used and use it to clear fields and heavy growth and it seems indestructible.

Bush Hog attached to Case tractor
Bush Hog attached to Case tractor

Finally, and the topic for this post, the Murray 40508×92  40″ mower which I bought used and damaged 7 years ago from a neighbor and have kept going with occasional ad hoc repairs and replacements.  Until last week when the mower drive belt kept slipping off the pulleys and all came to a halt.  The engine turns the drive belt and the belt turns two pulleys which are connected to the two blades which do the cutting.  So what was the problem?  Each pulley turns a jackshaft which turns a blade.  The shaft is held in position by a mandrel secured by 5 bolts to the mower housing/deck.  3 bolts on one mandrel were missing  and the 4th was loose.  So when the belt applied torque to the pulley the pulley lifted and the belt slipped off.  Replacing the bolts wouldn’t work – it was apparent that as individual bolts loosened the vibration of the blade had torn the metal housing to which the other bolts were attached, and as each bolt came off the vibration and damage increased.  A stitch in time would have saved nine.

Murray mower with mower housing removed
Murray mower with mower housing removed

It seemed I had several options – buy a new deck; buy a used deck; buy a replacement mower or have the deck fixed.  Internet search showed no new decks matching this part #, though comparable new decks >$400 before shipping.  On Craigslist I could buy a newer more powerful mower for $400.   eBay showed similar decks used for $70 to $100 before shipping cost of say $70.  And they probably would not fit and would have to be adapted.  So, could it be repaired?  Welding, regrettably, is a skill I do not (yet) have.  But there is a local shop which I previously used which does good work for reasonable cost.  I took it in and they said sure.  I asked cost and they said $30 if it took 30 mins. but not to exceed $60.

Two days later it was ready.  They decided that in addition to welding the torn housing together it was prudent to weld on two plates – total cost $55.

a view of the mower housing removed from the lawn tractor.
a view of the mower housing removed from the lawn tractor.

The welding was done to the housing to which the right pulley is attached.

this close up shows the 2 plates and the stitching of the torn material
this close up shows the 2 plates and the stitching of the torn material

I really felt foolish for having allowed this damage to progress but the welder, noting my embarrassment, said he does 4 to 5 mower decks a week and he showed me a newly arrived patient.  This was larger than mine with 3 pulleys driving 3 blades and the housing for the one pulley had completely disintegrated and major welding plate surgery was now needed.  So I felt a bit better.

I purchased new bolts and coated the threads with Loctite to discourage them from loosening.

close up showing all the bolts in place
close up showing all the bolts in place, there are 5 of them

The other drive pulley was distorted and so, while I was at it, I installed a new pulley.  The nut on a pulley can be difficult to remove because the pulley shaft turns as you apply pressure on the nut.  I remember in the 90’s I was unable to undo the nut on a generator so I took it to an auto shop and in a few seconds it was off – they used an impact wrench.  I bought an electric impact wrench and it has been invaluable for removing nuts on shafts.

impact wrench, loosened nut and new pulley
impact wrench, loosened nut and new pulley

So I decided to also examine and sharpen the mower blades.

underside of mower housing with blades revealed
underside of mower housing with blades revealed

The impact wrench loosened the two nuts securing the blades.  Since I had a balancing jig I decided to use it.

a jig to test if the weight of the blade is balanced, otherwise undue vibration
a jig to test if the weight of the blade is balanced, otherwise undue vibration

My father-in-law bought me my first bench grinder and instructed me how to use it.  They can be very dangerous if misused – if a fast revolving grindstone shatters, there will be injury.  I always wear extensive eye protection from my experience some years ago when I was grinding the valves of an Accord and a metal speck flew under my conventional glasses and lodged in my eye and this necessitated a visit to the emergency room.

my bench grinder - if a fast revolving grindstone shatters, there will be injury
my bench grinder mounted on a platform in the basement

All that remained was to re-install the mower housing.

re-installing the housing
re-installing the housing

And it works just fine!

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