Dave, Wayne, All,
The axle in the GMC trolley/handcar is NOT magnetised.
A magnetic substance it is, as tested by "CRANKY".
They are GMC products, tho.
ELEC-TRACTION POWERED
G.M.C.
STREET CAR
General Models Corporation,
West Chicago, Illinois(See Pix below)
The 'Magne'Traction' sticker on the side is an after sale add on, possibly a cutout from a LIONEL catalogue.
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The field coil is energised by the segmented wheels which in turn attract the edge of the rounded 'armature/axle'.
Current/magnetic attraction is interrupted py the plastic segment of the commutator/wheels.
It coasts until the next wheel copper segment makes rail contact.
The cycle repeats.
The rear wheels are plastic.
If they were metal, it would effectively(sp?) short out the armature, and apply full power/current to the field coil.
The copper segments on the wheels make contact with the axle/frame, as does one side of the motor coil and headlamp.
The other side of the lamp and coil is connected to the center rail slider.
The trolley DOES need a push start by a '0-5-0 switcher', and will stall on turnouts/crossings/anywhere there in a nonconductive rail, (center or outside).
The headlamp does flash off and on 2x each revolution of the wheels.
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... Under no load, it would spin at 60 Hz or 3600 rpm. ...
No. Wayne, it will not, due to it's construction and design.
(B.T.D.T.!)
IMO, it woild be kind of difficult (tho not impossible) to 'benchtest'.
You would meed a feeler gauge connected to one power/test lead, the other power/test lead connected to the center rail slider.
Apply power, Hold the feeler gauge against the segmented wheel, and with your third hand spin the armature/axle/wheel assembly to kick-start.
You
could make a quick check of the headlamp/bulb by connecting the feeler gauge test lead directky to the frame.
Don't leave it connected that way for long, tho, or you will let out all the 'magic smoke' in the field coil.
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Dave,
My Street Car is MUCH s-l-o-w-e-r than your "LSR Hand Car"....

This could be due to the fact that my street car has not been out of the box for ~15 years and the test track conditions.
The 'Unknown Chassis' may be an upgrade or a later version of a GMC power unit.
It appears to mount thru the axles like the GMC hand/street/cars to an outside frame.
The center rail sliders are the same as on Wayne's pic and mine.
The R.H screw is identical to the mounting screw(s) holding the plastic body on my trolley.
Underview of mine is identical to the ones pictured by you and Wayne.