They look like the chemical pumps that are used in the oil field around here, the ones I've seen are yellow, and some blue, but both with two adjustment knobs, one for stroke and one for speed.
If they are the same or operate the same they are some skookum pumps as we use them all day everyday out in the open. A failed pump could cause around a $5000 failure to the well, if the pumper who checks the well daily doesn't check the pump, which happens a lot.
These pumps need the chemical above the pump, and it would be wise to install the line pressure bleeder as sometimes they suck air and cause it not to pump.