I'm guessing to regulate the speed at which the lift goes up.

I had a buddy make a lift for his log splitter. I borrowed his log splitter, rolled about a 70lb log up to the lift, hit the lever to raise the log up and launched the log about 10 feet the other side of the log splitter. When I complained about it to him he said "yeah you got to pull that lever slowly". I bought the log splitter from him a few years later and removed that damn log launcher.

 

I have the same setup (Hyd Cyl & Hyd/Air Foot Pump) and going up in not an issue as the Hyd/Air Foot Pump builds pressure rather slowly. I'm having to assume it's the trip back down that might be the issue.

 

Great built!

 

Its probably a one way flow control. Going up it’s full flow and closed needle valve has no effect on oil. Once the table is up, it stays up until you open the valve and let oil back out, lowering your bike.