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Saturday, October 26, 2019

A McCulloch Model MT2026 Corded String Trimmer




The trimmer hub is a disaster, and replacement parts are no longer available. There'll be no restoring this item to operability. I figure I'll take it to pieces just for the heckuvit. Maybe there'll be something of it that's worth salvaging.

The Hub


The hub's outer shell is a piece of wreckage. It appears that a repair to the torn out trimmer line exit holes has been attempted, to poor effect. The hub spring is an ill-fitting kludge -- not the original spring. I don't know what to make of the translucent sleeve over the trimmer line spool. How that arrangement could ever bump-feed trimmer line is beyond me.

The Business End


There's a steel rod bail holding the safety guard in place. (The bail rod is 4mm diameter.) With that bail pried loose and removed, the safety guard can be removed. The motor housing can then be opened up.

Opening Up The Motor Housing

The motor housing is fastened together by ten 4mm threading screws, No. 2 Phillips recess. One of the screws is concealed under the ID label. The two uppermost screws are 13mm long. The other eight screws are all 18 mm long.

Opening up the motor housing reveals two prominent features of the machine -- the handle length adjuster and the motor itself.

Handle Length Adjuster


There's a latch/detent affair that enables the handle shaft to have one of four different lengths. The length increments are just shy of one inch.

The latch and the detent lever are spring loaded by coil springs. (I'll salvage the springs.) It's a diabolical thing to reassemble if it springs apart on you, which it's very likely to do.

The Motor


The motor is quite robust looking. (It still works, by the way.) Motor rating is 120 VAC, 3.2 A, 10,000 rpm.

The motor mount bracket is fastened to the housing by two 4mm threading screws, No. 2 Phillips recess. That fan/hub on the output end of the motor appears to be press-fitted on. I can see no non-destructive way to remove it.

Motor Fan/Hub Removed

I bored into the centre of the plastic fan/hub so I could get a puller's nose to contact the motor's shaft. That got the fan/hub started coming off. From there, I was able to pry the fan/hub off the rest of the way. Here's a view of the motor out of its housing along with its detached fan/hub.


The motor's shaft is 8mm diameter, with splines that make for an interference fit with the fan/hub's bore. Shaft length is 15/16".

I rigged the motor for a no load current draw measurement, and a photo-tachometer reading. I got about 650 mA  at about 27,000 rpm. Evidently, the 3.2 A, 10,000 rpm rating represents full load values.

Anyway, I now have a very nice little universal motor that I can think of no possible use for.

The Handgrips


The lower handgrip is fastened by a single M6 x 52mm carriage bolt and wingnut. There's a flat washer under the wingnut.

The upper handgrip is held together by six 4mm threading screws, No. 2 Phillips recess. The two screws nearest the trigger are 13mm long; the remaining four screws are 18mm long

The Trigger Switch


The red trigger acts on a momentary slide switch. The slide switch is made by Defond. It's rated at 11 A, 125 VAC, 5.5 A, 250 VAC. Its terminals are 3/16" male spade terminals.

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So there we have it -- the whole thing dismantled. Here's what all I salvaged:

  • Three compression springs.
  • Motor.
  • Slide switch.
  • An M6 x 52mm carriage bolt with wingnut and flat washer.
  • A 25 1/4" length of 7/8" diameter steel tubing.
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