A Pumps
 

Hi there, can any one please explain what a pumps are on the 737 series a/c

Thanks in advance.

The 200 has two engine driven pumps for A and two electric for B like the 727. Then the 300 on have an engine driven pump and electric pump in each system.

roughly...
 

737 has 3 hyd systems: A,B and a sby which can be switched on manually.
each A/B has one eng driven hyd pump and one elec driven powered by the other engine's generator.
A system has gear, altn brake, flaps, flt cont, half the spoliers, rev, one AP
B has brake, alternate gear, flt cont, rev, half the spoilers, the other AP

so the "A" pumps are the pumps powering/pressuring system A ..... and on the "classics" they are switched off for push-back to prevent damage to the nose-gear......

Thanks for the replys!

A pumps on a B732 were EDPs or Engine driven pumps...operated from the Engine & mounted on the gearbox.

The switches were placed on at all normal times to increase the life of the depressurising solenoid.

On the B733 onwards A & B system had one EDP & one EMDP [Electric motor driven pump] each.

regds
MEL

In addition to FCS explorer and a minor correction. A system the gear and B system the flaps. The standby can be activated manually or automatically to power thrust reversers rudder and leading edge flaps/slats (extend only). Automatic operation of the standby is initated with loss of system A or B or rudder pressure reducer system fails in low pressure mode(classic),and flaps extended. In aus we always push back with a nose gear steering lockout pin installed however if that wasnt available we would depressurize system A.