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Company Culture ꄲ Fluid Power ꄲ Rexroth A7VO55LRDS/63L-NZB01-S Variable Axial Piston Pump (Part No. R902211892)

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Rexroth A7VO55LRDS/63L-NZB01-S Variable Axial Piston Pump (Part No. R902211892)

Bosch Rexroth A7VO series bent-axis variable piston pump, nominal displacement 54.8 cm³/rev, nominal pressure 350 bar / peak 400 bar, LRDS control (power control + pressure cut-off + load sensing), left-hand rotation, Series 63, for open-circuit hydrostatic drives in construction machinery.

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Product Details

1. Product Overview

The A7VO is a bent-axis design axial piston variable single pump by Bosch Rexroth, built for hydrostatic drives in open circuits. One axial tapered piston rotary group is integrated in the housing; the flow is proportional to the input speed and the displacement, and can be steplessly varied by adjusting the bent axis.

This model features LRDS control, combining three regulating functions:

Power control (LR): automatically adjusts displacement according to operating pressure along a hyperbolic characteristic so that a given drive power is not exceeded, making optimum use of available engine/motor power;
Pressure cut-off (D): when operating pressure reaches the cut-off setting, the pump automatically swivels back to minimum displacement, maintaining only stand-by pressure at high pressure to reduce relief losses;
Load sensing (S): the LS regulator adjusts displacement according to the pressure drop across the external directional valve's metering orifice, delivering flow on demand and maintaining a constant Δp so that flow is independent of load pressure.

The pump is compact and robust, widely used in excavators, cranes, concrete pump truck booms, aerial work platforms and other mobile and stationary hydraulic systems.

2. Specifications

表格

Item	Specification
Brand	Bosch Rexroth
Series	A7VO (Series 63)
Design	Bent-axis axial piston variable single pump, open circuit
Nominal displacement Vg max	54.8 cm³/rev
Min. displacement Vg min	0 cm³/rev
Nominal pressure	350 bar
Peak pressure	400 bar (single period 10 s, cumulative ≤300 h)
Min. pressure on high-pressure side	10 bar
Rated speed (at Vg max) nnom	2500 rpm
Max. speed 1 (at Vg < 0.74 Vg max) nmax1	3400 rpm
Max. speed 2 (limit speed) nmax2	3750 rpm
Max. flow (at Vg max, nnom) qv	137 L/min
Max. power (at Vg max, nnom, Δp=350 bar) P	80 kW
Max. torque (at Vg max, Δp=350 bar) T	305 N·m
Shaft rotation	L (counter-clockwise, viewed from drive shaft end)
Shaft end	Involute spline
Seals	NBR
Control	LRDS: power control (LR) + pressure cut-off (D) + load sensing (S)
LS differential pressure Δp setting range	14–25 bar (factory default 18 bar)
Power control start-of-control range	50–220 bar
Working port A(B)	SAE J518 1¼", M14×2
Suction port S	SAE J518 3", M16×2
Load-sensing port X4	M14×1.5 (must connect external LS signal)
Control fluid drain T1	M12×1.5 (must connect to tank)
Approx. mass	Approx. 25 kg
Hydraulic fluid	Mineral oil (RE 90220); environmentally acceptable fluids (RE 90221); HF fluids (RE 90223)

Theoretical values per A7VO Series 63 official data sheet RE 92202 (02.2015). The LRDS version requires an external LS directional valve (metering orifice, not included in delivery); T1 control drain must be plumbed separately to tank. Power setting must be specified in plain text at ordering: drive power P [kW], speed n [rpm], max. flow qv [L/min].

5. Model Information

Material / Ordering number: R902211892
Type code: A7VO55LRDS/63L-NZB01-S
Product description: Rexroth A7VO series bent-axis variable axial piston single pump, size 55, LRDS control (power control + pressure cut-off + load sensing), Series 63, left-hand rotation, NBR seals, special version (-S).
Official catalog description: A7VO is a variable displacement pump with an axial tapered piston rotary group in bent-axis design for hydrostatic drives in open circuits.
Material number note: R902211892 is the ordering material number for type code A7VO55LRDS/63L-NZB01-S. The same type code may carry cross-reference material numbers across production batches; please rely on the number on your machine nameplate. If you have questions about suffixes such as NZB01, -S or cross-reference alternatives, please contact us by email.
Series features:
- Bent-axis axial tapered piston rotary group, proven design, robust and durable
- Flow proportional to speed and displacement, infinitely variable down to zero
- LRDS combined control: power control for overload protection + pressure cut-off for safety + load sensing for flow on demand
- Load sensing maintains constant Δp; flow is independent of load pressure, saving energy and improving controllability
- Pressure cut-off unloads the pump at high pressure, reducing relief losses
- Compact, high power-to-weight ratio; suitable for mobile and stationary applications
Related sizes in series: A7VO28 (28.1 cm³), A7VO80 (80 cm³), A7VO107 (107 cm³), A7VO160 (160 cm³)
Matching products: Requires LS-type directional valves (e.g. Rexroth M4-12, RM series); in LUDV systems the pressure cut-off is integrated in the flow-sharing control block; electronic control can be paired with BODAS controllers
Official document: Bosch Rexroth data sheet RE 92202 "Axial piston variable pump A7VO Series 63, Sizes 28…160"

6. Why Choose Us

Exact model match: We verify supply against your full type code and material number R902211892; the LRDS version is not substituted with DR/LR single-control versions.
Authorized channel supply: Bosch Rexroth hydraulic pumps supplied through regular channels, with product documentation available on request.
Selection support: We help confirm displacement, pressure, speed, power setting and LS valve matching align with your machine's duty cycle.
Delivery & after-sales: Quotation, lead-time confirmation and order follow-up provided; for any parameter questions or alternative options, please contact us by email.

7. FAQ

Q1: What is the displacement? Is it a single or double pump?

A: The A7VO55 is a variable single pump with nominal displacement 54.8 cm³/rev, adjustable down to 0. It differs from the A8VO series, which is a double pump with two rotary groups.

Q2: What does LRDS control mean?

A: LRDS = power control (LR, hyperbolic characteristic limits input power) + pressure cut-off (D, unloads to minimum displacement at high pressure) + load sensing (S, flow on demand via external valve orifice Δp). Power control overrides load sensing, and pressure cut-off overrides power control.

Q3: What is the benefit of load sensing (LS)?

A: The LS regulator maintains a constant pressure drop (Δp, factory default 18 bar, adjustable 14–25 bar) across the external directional valve's metering orifice; the pump delivers only the flow demanded by the actuator, flow is independent of load pressure, avoiding high-pressure overflow losses.

Q4: What does left-hand rotation (L) mean?

A: L indicates counter-clockwise rotation when viewed from the drive shaft end, as opposed to R (clockwise). The pump must be installed with the correct rotation matching the engine/motor; incorrect rotation can damage the pump.

Q5: What are the nominal and peak pressures?

A: Nominal pressure 350 bar, peak pressure 400 bar (single period ≤10 s, cumulative ≤300 h), per A7VO Series 63 data sheet RE 92202.

Q6: Are there special installation requirements for the LRDS version?

A: As a pressure cut-off version, the control fluid drain port T1 must be plumbed separately to tank (not plugged); port X4 must connect to the LS signal of an external load-sensing directional valve; ports X3, Y3, X1 are plugged in the standard configuration. Power setting must be specified at ordering: drive power P [kW], speed n [rpm], max. flow qv [L/min]. If in doubt, please email us for verification.

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