One of the basic things you have to know about any machine which is based around rotating shafts (and thus flywheels and often cams) is which direction it rotates. For some machines, such as platen presses, this can be very difficult to figure out. Fortunately, for the Barth it's easy.
First, you can see by inspection that the main Cams turn in the same direction as the Flywheel. Of these main Cams, the Pump Cam is most clearly a one-directional cam. Its its direction of rotation is top-away.
You can also determine the direction of rotation by reading Barth and Lietze's US patent 376,765 (issued 1888), which is the basic patent for this machine. In it, Figure 17 indicates the direction of camshaft rotation with a helpful arrow.
Here's the Pump Cam. You can see both the Cam itself (on which the Cam Roller rides) and, bolted to each side of it, the Shoes off of which the Lever drops. (In a caster, you can't have the Pump Cam Roller just roll off a drop - that's not abrupt enough. So for the last bit of rotation the Lever is raised not by the Roller but by riding up on Shoes - from which it can drop instantly. The directionality of the Shoes is apparent.
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