The tamei [parts] of a wagon [are]:

The yoke of metal (the yoke was the part that went across and over the animals' shoulders and necks),

and the cross-piece (this was a long wooden pole that ran parallel to the yoke, and was beneath the animals necks)

and the wings (these were curved attachments at the ends of the cross-piece)

that hold the reins,

and the iron

that under the neck of the animal (this was a sort of collar that helped protect the animal's neck from the straps of the harness)

the pulling ring (this was a metal ring in the middle of the yoke to which the the wagon would be connected)

and the harness (this encircled the neck of the animal; some say it went around the animal's body, and others say it was a pin that kept the wagon from making too tight of a turn),

and the plates (these curved pieces of metal resembled serving platters; they sat beneath the yoke on the neck of the animal),

the clapper (of the cowbell),

and the hook (this was used to hold down the wagon's load),

and the nail that connects all of them.

פרק יג משנה ה

The tahor [parts] of a wagon [are]:

The [metal] plated [wooden] yoke,

and wings that are made for decoration,

and tubes (these were small mtel tubes that hung from the harness)

that make noise (since their primary purpose is for decoration, these are tahor)

and the (decorative) lead [balls]

that are on the side of the animal's neck,

the [metal] rim of the wheel,

and the sheet metal (some say this protected the wood of the wagon from its load),

and the (decorative) plating,

and all the other nails

are tahor.

The animal's shoes (unlike modern horseshoes, these were larger and had a receptacle; it was sometimes used by soldiers to hold liquids),

of metal are tamei,

of shaam are tahor (some say this was a bamboo-like reed grass, others say it was cork; it wore out to quickly to be of service to humans and so is not tamei).

The sword,

from when is it susceptible to tumah?

From one polishes it. (Some say this refers to a sword that is being restored after having become too rusted to use; according to these opinions the polishing referred to hear is an abrasive process that removes the rust.  Other opinions hold that this refers to the final step in the manufacture of a sword, when it is stropped on leather with oil.)

And the knife

from when one sharpens it. (Unlike a sword, a knife must be very sharp to have any utility, so if being restored or manufactured, this step is required before it will be susceptible to tumah.)