Ignoramus2810 wrote:

On 3 Mar 2005 13:59:36 -0800, wrote:


Mid-range is a belt drive with an oil-filled compressor, these have
alloy pumps with iron sleeves. I've also seen a direct drive with the
same features, I wasn't able to find a motor plate with the speed,
though.

High-end is the all-iron pump with belt drive, these tend to be on the
heavy end for portable operation, you aren't likely to sling one into
the back of a pickup single-handled.



Stan, how can I tell a mid-range unit from a high-end unit by just
looking at them? I am curious if my Curtis compressor is high end or
midrange, according to your description.


If it has an oil pump (sure giveaway is if there is an oil pressure
gauge or oil filter) that is one big sign. Another is if it has unloaders
on the cylinder head. These are generally diaphragm-operated, and hold
the intake valves open while the motor is spinning up. Some also have
an interlock to unload the compressor if the oil pressure fails. Disc
valves are another high-end design feature, but it is pretty hard to tell
the valve type from the outside.

Jon