Transit Mixer Eaton 4623 5423 6423 7620 pump
Hydraulic Eaton concrete mixer truck pump 4623 5423 6423 7620
Nominal Pressure: 420 bar (6000 psi) and Peak Pressure 480 bar (7000 psi)
Displacement from 63.7 to 124,8 cm3/r (3,89 to 7,62 in3/r)
Eaton has the lead position in providing reliable and durable system solutions for transit mixers—vehicles on which downtime can mean disaster. Whether the truck is traveling down a highway or idling at a traffic light, the drum must maintain a consistent rotation speed. That’s no problem when Eaton is on the inside. Eaton pump and motor provide the high pressure and high flow required to keep drums rotating.
Drive shafts – a wide variety of options are available to suit every need.
High strength swash plates on variable pumps and motors – resist deflection under high load.
High strength cast iron housings – provide greater noise damping and wall strength.
High flow check valves in pumps – keep the system primed with minimal pressure drop.
Charge pumps on pumps – gerotor type, several displacement options are available to suit the needs of every application. All cast iron construction.
Cartridge shaft seal – lends itself to easy serviceability. Mechanical face seal design tolerates high speed and high case pressures.
Table of values (theoretical values, without efficiency and tolerances; values rounded)
|Eaton ACA pump||3923||4623||5423||6423||7620|
|Maximum Shaft Speed*||Rpm @ 18°||4160||4160||3720||3720||2775|
|gpm @3500 psi||67.3||79.2||84.1||99.1||87.9|
|lpm @241 bar||255||300||318||375||333|
|lb-in @3500 psi||2346||2786||3285||3900||4552|
|Nm @241 bar||265||315||371||441||514|
Pump performance calculated at 96% efficiency.
*The maximum pump shaft speed may be limited by the charge pump speed rating.
** Nominal Pressure: Max delta system pressure at which component fatigue does not occur (pump life estimated by bearing life).
*** Peak Pressure: Max operation pressure which is permissible for a short duration of time (t < 1 sec).
Eaton heavy duty variable pumps
The Eaton heavy duty variable displacement pump contains a rotating cylinder barrel and pistons. The displacement control directs control pressure to the two servo pistons that position the swash plate. The variable pump is powered into stroke and springs, on the servo pistons, bring it out of stroke. The swash plate pivots on tapered roller bearings. A bolt-on charge pump, with a cartridge type charge pressure relief valve, is available in four displacements. One lever controls direction, varies speed and provides dynamic braking. This ease of operation, in conjunction with a wide variety of control options, allows Eaton hydrostatic transmissions to be readily adapted to many applications.
Power Limiter Valve Operation
Power limiter valves (PLV) are high pressure relief valves built into the pump’s end cover. When pressure in the high pressure loop gets too high, the PLV opens to the pump case. Besides an immediate drop in the loop high pressure, the open PLV also causes control pressure to drop. This in turn allows the centering springs on the servo pistons to bring the pump out of stroke until the pressure drops to the relief valve setting and the PLV closes. The PLV will also act as a check valve to prevent cavitations in the event of a rapid pressure rise and hose expansion.
A motor with integral shuttle valve is used in conjunction with the power limiter valve pump.
Tandem Pump Applications
Tandem pumps are most typically used in applications where two independent sources of hydraulic power are required while taking advantage of using only one power source to drive the two pumps. This saves on the expense of driving two pumps by eliminating the split drive gear box or eliminating another power source such as a second engine or motor. Tandem pumps can be used on machines such as track drive equipment where independent power is required at each track. Speed and power can be controlled to each side of the vehicle for steering and vehicle speed control both in forward and reverse directions. Tandem pumps can also be used to create the equivalent flow of one larger displacement pump by combining the flows of the two pumps. This is an economic advantage over using a single large displacement pump. Tandem pumps may also be used in industrial, construction or mining applications where several sources of hydraulic power are required while taking advantage of using only one power source to drive the two pumps.
The variable displacement pump provides a flow of high pressure oil. Pump output flow can be varied to obtain the desired motor output speed. For example, when the pump’s displacement is zero, no oil is pumped and the transmission’s motor output shaft is stopped. Conversely, maximum pump displacement produces maximum motor shaft speed. The direction of high pressure flow can
also be reversed; doing so reverses the direction the motor output shaft rotates. A charge pump is integrated into the piston pump and driven by the shaft of the piston pump. The drawing illustrates a suction filtration circuit. Eaton recommends a suction filter without a bypass valve. The charge pump has a Low Pressure Relief Valve that regulates the output pressure.