989a. Both of these were marked "train key", this first one is a reverser key, it puts the locomotive in neutral, forward or reverse.
989b. Update: Looks like this is actually a water meter lid key, two examples can be seen here and here.
990. Bagno handcuffs, more info on this device can be seen on the bottom of this site.
991. Oil cups, used to lubricate bearings, this page has some cut-away views that shows how they work.
Oil cups, grease cups, and priming valves:
992. This is an inside view of a coin slot.
993a. Both of these tools are Windsor beaders, used to make patterns in wood.
993b. This one is patent number 326,435.
From Jim Brown's collection.
994. A tooth from the inside of an International Harvester combine:
Last week's set is seen below, click here to view the entire post:
More discussion and comments on these photos can be found at the newsgroup rec.puzzles.