Andy Hall wrote:
On 2008-05-16 17:52:44 +0100, "The Medway Handyman"
said:

I'm assuming this machine has a swash plate pump, unlikely to be
anything else (just looked & it does). There are two parts to the
head, the pressure head & the crank, called housing 1 & housing 2 on
this diagram


WHat is a swash plate pump and how does it work? Enquiring minds
need to know.

Early high pressure pumps like the American CAT or the German Speck work by
having pistons driven by a crankshaft, rahther like a car engine. They were
extreemly durable, but best run at around 1400rpm, and expensive to make.
http://www.catpumps.com/pages/aboutus_work.html

The swash plate or axial pump can be run faster, so can use a cheaper 2800
rpm motor and are much cheaper to manufacture. They also have the advantage
that performance can be changed just by altering the swash plate angle, so
you make one pump and have 6 swash plates.

Three piston swash plate pumps are the norm, two piston really need a
pulsation damper, four piston are a bit of overkill.

Good picture here http://www.animatedsoftware.com/pumpglos/wobble.htm This
shows the valves integral with the pistons, they are usually in the head
casting.

HTH



--
Dave - The Medway Handyman
www.medwayhandyman.co.uk