Rexroth A4VTG Piston Pump with Good Reviews

Closed circuit
Series 32
Sizes 71, 90
Nominal pressure 5800 psi (400 bar)
Maximum pressure 6500 psi (450 bar)
Control device: (HW) Proportional control hydraulic, mechanical servo, hexagon shaft with lever to the rear.
(EP) Proportional control electric, with emergency actuation and spring return.

For the drum drive in mobile concrete mixers A4VTG071, A4VGT090 series.
-Variable axial piston pump of swash plate design for hydrostatic drives in closed circuit
-The flow is proportional to the drive speed and displacement.
-The flow increases as the angle of the swash plate is adjusted from zero to its maximum value.
-Flow direction changes smoothly when the swash plate is moved through the neutral position.
-Two pressure-relief valves are provided on the high pressure ports to protect the hydrostatic transmission (pump and motor) from overload.
-The high-pressure relief valves also function as boost valves.
-The integrated boost pump acts as a feed pump and control pressure supply.
-The maximum boost pressure is limited by a built-in boost pressure-relief valve.
-Tapered shaft option for direct drive shaft yoke installation.