Bosch Rexroth RKP-PQ Replacement/Upgrade for RKP Series

Product Overview

Bosch Rexroth RKP-PQ Replacement/Upgrade for RKP Series: Seamless Transition from Legacy Hydraulic Control Systems

The Bosch Rexroth RKP-PQ is a precision P/Q control amplifier card engineered for the RKP radial piston pump series — one of the most widely deployed variable-displacement hydraulic pump platforms in industrial press systems, injection molding machines, die-casting equipment, and heavy-duty test rigs. As legacy RKP-PQ units reach end-of-service life or become increasingly difficult to source through OEM channels, plant engineers and procurement teams face a critical decision: reactive replacement under emergency downtime conditions, or a planned, compatibility-verified upgrade that protects production continuity.

TOPNLMS supplies the RKP-PQ amplifier card as a direct replacement and upgrade solution for existing RKP series installations. Each unit is sourced from verified supply channels, pre-shipment tested, and backed by a 12-month warranty — giving your maintenance and procurement teams the confidence to plan ahead rather than scramble.

Compatibility Comparison Table

Seamless Upgrade Solutions

A successful RKP-PQ replacement rarely happens in isolation. In most hydraulic press and injection molding control architectures, the amplifier card interfaces directly with the machine’s main PLC — commonly a Siemens S7-300 or S7-400 series controller — through analog output modules such as the SM 332 or SM 331. When upgrading the RKP-PQ, it is good practice to simultaneously verify the condition of the analog I/O modules driving the pressure and flow setpoints, as degraded signal quality from aging SM 332 AO cards can cause erratic P/Q behavior even after a new amplifier card is installed.

In systems where the hydraulic unit is controlled via a Profibus DP network, the Bosch Rexroth VT-HACD proportional amplifier or associated fieldbus gateway modules may also be part of the upgrade scope. Ensuring that the Profibus DP address settings and baud rate configuration on the gateway match the existing network parameters eliminates communication faults during commissioning.

For machines using older Bosch Rexroth VT-SR2 or VT-VSPA2 servo amplifier cards in adjacent hydraulic axes, a coordinated replacement plan covering both the RKP-PQ and any co-located amplifier cards reduces total downtime to a single planned maintenance window rather than multiple emergency interventions. Similarly, if the hydraulic control cabinet houses a Bosch Rexroth VT-HNC100 axis controller or a VT-HACD-1 digital hydraulic controller, verifying firmware compatibility with the replacement RKP-PQ card before installation prevents unexpected parameter conflicts.

On the power supply side, the 24 VDC rail feeding the RKP-PQ should be verified with a calibrated multimeter before installation. Aging Siemens SITOP PSU100S or equivalent DIN-rail power supplies that show voltage ripple above specification can cause instability in the new amplifier card’s internal reference circuits. Replacing a marginal power supply unit at the same time as the RKP-PQ is a low-cost step that protects the investment in the new card.

Where the hydraulic system feeds a servo-hydraulic test bench or a precision forming press, the RKP-PQ replacement may also be the right moment to audit the condition of the proportional pressure relief valve solenoid and its associated Bosch Rexroth VT-VRPA2 amplifier. Worn solenoid coils or drifted amplifier gain settings can mask the performance improvement delivered by a new RKP-PQ card. A full system calibration — covering pump displacement, pressure setpoint accuracy, and ramp time parameters — should follow any amplifier card replacement to confirm that the hydraulic axis meets its original performance specification.

For facilities managing a broader Bosch Rexroth hydraulic platform, TOPNLMS also supplies related components including VT-VSPA2 proportional amplifiers, VT-SR2 servo amplifier cards, VT-HNC100 digital axis controllers, and RKP series pump assemblies, supporting a consolidated procurement approach that reduces lead time and simplifies incoming inspection.

Retrofit Guidance FAQ

Q: Do I need to modify the existing wiring harness when replacing the RKP-PQ?
A: In the vast majority of RKP series installations, the replacement RKP-PQ card uses the same connector pinout as the original unit. The existing wiring harness can be reconnected directly. Always verify pin assignments against the machine’s electrical schematic before powering up.

Q: Will the PLC program need to be modified after the replacement?
A: Typically no. The RKP-PQ replacement maintains the same analog signal interface (±10 V or 4–20 mA setpoint inputs), so the PLC analog output scaling and the hydraulic axis function block parameters remain valid. If the original unit had custom gain or ramp settings adjusted during commissioning, document those values before removal and re-enter them on the replacement card during startup.

Q: Is the replacement compatible with Profibus DP or other fieldbus architectures?
A: The RKP-PQ itself operates on analog setpoint signals. Fieldbus communication (Profibus DP, CANopen, or EtherNet/IP) is handled upstream by the PLC or a dedicated hydraulic fieldbus gateway. The replacement card does not alter the fieldbus architecture and requires no changes to network configuration.

Q: How much physical space does the replacement card require in the control cabinet?
A: The RKP-PQ replacement matches the original card’s form factor and DIN-rail or panel-mount footprint. No cabinet modifications, additional mounting rails, or enclosure extensions are required.

Q: What commissioning steps are recommended after installation?
A: After physical installation and wiring reconnection, perform a low-pressure functional test to verify pressure setpoint tracking, then a full-range Q (flow) ramp test. Confirm that the pump reaches target pressure and flow within the original ramp time parameters. Log the results as a baseline for future maintenance reference.

Warranty Assurance

Every RKP-PQ unit supplied by TOPNLMS is covered by a 12-month warranty from the date of shipment. Prior to dispatch, each card undergoes a pre-shipment functional check to verify power-up integrity, signal response, and output stability. Units that do not meet specification are quarantined and not shipped.

In the event of a warranty claim, TOPNLMS provides a replacement unit or repair support with a target response time of 1–3 business days for initial assessment. Customers are not required to return the defective unit before a replacement is dispatched in confirmed warranty cases, minimizing the impact on production schedules.

Stock is maintained in Xiamen, China, with express international shipping available to most industrial regions. Typical transit times are 3–7 business days for air freight to Europe, Southeast Asia, and the Middle East. Expedited same-day dispatch is available for orders confirmed before 14:00 CST.

For procurement teams requiring documentation, TOPNLMS can provide a packing list, commercial invoice, and certificate of conformance with each shipment. All units are packed in anti-static protective packaging with foam cushioning to prevent transit damage.

To confirm stock availability, request a quotation, or discuss a multi-unit procurement plan for your maintenance inventory, contact the TOPNLMS technical sales team directly.