Yaskawa HW9381633-A Replacement for HP20 HP20D L-Axis

Product Overview

Yaskawa HW9381633-A Replacement for HP20 HP20D L-Axis: Seamless Transition & Legacy System Compatibility

The Yaskawa HW9381633-A is the OEM L-Axis RV speed reducer designed for the Motoman HP20 and HP20D 6-axis industrial robot series. As these platforms age and original spare parts become increasingly scarce, many maintenance engineers and procurement teams face the challenge of sourcing a verified replacement that preserves wrist-axis precision, load capacity, and backlash specifications without requiring mechanical rework or controller re-parameterization.

TOPNLMS supplies the HW9381633-A — also cross-referenced as HW0387753-C — as a direct-fit replacement unit. Whether your facility is running a legacy HP20 cell in automotive spot welding, arc welding, or material handling, this reducer slots into the existing L-axis housing with no modification to the arm casting, output flange, or mounting bolt pattern. The gear ratio, output torque rating, and moment of inertia values are preserved, meaning your YRC1000 or DX200 controller does not require axis calibration changes beyond the standard zero-point restoration procedure.

For plants operating mixed fleets that include the HP20D variant alongside HP20 units, the HW9381633-A is interchangeable across both robot bodies, simplifying your spare parts inventory and reducing the number of unique SKUs your maintenance team must stock. This is particularly valuable in high-throughput production environments where unplanned downtime carries significant cost.

Compatibility Comparison Table

Seamless Upgrade Solutions

A successful L-axis reducer replacement on the HP20 or HP20D is rarely a single-component job. In practice, the maintenance window is also the right time to inspect and, where necessary, replace adjacent components that share the same service interval or that are accessed during the same disassembly sequence.

The S-Axis and U-Axis speed reducers — HW9381634-A and HW9381635-A respectively — are commonly addressed in the same planned shutdown, since the arm must be partially disassembled to access the L-axis housing. Replacing all three reducers in a single outage eliminates the risk of a second unplanned stop within the same maintenance cycle.

The Yaskawa SGMRS series servo motor that drives the L-axis should be inspected for bearing wear and encoder integrity at the same time. If the motor is approaching its rated service hours, pairing the HW9381633-A reducer replacement with a motor overhaul or exchange prevents a repeat intervention. The motor connector and encoder cable — part of the HP20 internal wiring harness — should be checked for insulation degradation, particularly in high-cycle welding applications where thermal cycling accelerates cable fatigue.

For facilities migrating from older DX100-controlled HP20 cells to a DX200 or YRC1000 platform, the reducer swap is often performed concurrently with the controller upgrade. In this scenario, the JZNC-YRK01-1E rack and associated JANCD-YSF21-E safety board are typically replaced as part of the controller migration, and the axis parameter files must be re-loaded to match the new hardware configuration. The HW9381633-A is fully compatible with both controller generations, so no reducer-specific parameter changes are required beyond the standard zero-point calibration.

Grease replenishment is mandatory after any reducer replacement. Yaskawa specifies Molywhite RE No. 00 grease for the HP20 L-axis reducer cavity. Ensure the correct fill volume is applied per the maintenance manual to avoid premature wear or overheating. The grease nipple and drain plug should also be replaced if they show thread wear.

If your HP20 cell uses a Motoman NX100 or XRC controller in an older installation, note that the mechanical interface of the HW9381633-A remains compatible, but the controller’s axis parameter set will need to be verified against the robot’s original configuration file before recommissioning. TOPNLMS recommends retaining a backup of the controller parameters before any mechanical intervention.

For facilities that maintain a broader Yaskawa robot fleet — including MA1440 arc welding robots or MS80W spot welding variants — the procurement of the HW9381633-A as a pooled spare across multiple robot models may be feasible if the L-axis reducer specification is shared. Confirm the part number against each robot’s maintenance manual before pooling inventory.

Retrofit Guidance FAQ

Q: Does replacing the HW9381633-A require reprogramming the YRC1000 or DX200 controller?
A: No controller reprogramming is required. The axis parameters remain unchanged. Only the standard zero-point restoration (mastering) procedure must be performed after the reducer is installed and the arm is reassembled. Follow the Yaskawa HP20 maintenance manual section on L-axis mastering.

Q: Is the wiring harness affected during L-axis reducer replacement?
A: The internal motor power and encoder cables routed through the L-axis arm section must be carefully managed during disassembly. They are not replaced as part of the reducer swap, but should be inspected for chafing or connector wear. Reconnect and secure all cables per the original routing before reassembly.

Q: What communication protocol does the HP20 use, and does the reducer replacement affect it?
A: The HP20 uses Yaskawa’s proprietary MECHATROLINK-II or EtherNet/IP communication depending on the controller generation. The reducer replacement has no effect on the communication layer. Network configuration and I/O mapping remain unchanged.

Q: Will the HW9381633-A fit in the same physical space as the original reducer?
A: Yes. The HW9381633-A is dimensionally identical to the original L-axis reducer. No modifications to the arm casting, cover plates, or cable management brackets are required.

Q: What is the recommended procedure for sourcing and testing before installation?
A: TOPNLMS performs outgoing inspection on each unit prior to shipment. Upon receipt, verify the part number label, inspect for shipping damage, and confirm the output flange rotates smoothly by hand before installation. Do not install a unit that shows signs of impact damage to the housing.

Q: Can this reducer be used as a direct replacement for HW0387753-C?
A: Yes. HW0387753-C is a superseded cross-reference for the same L-axis reducer assembly. The HW9381633-A is the current Yaskawa part number and is the correct replacement for both references.

Warranty Assurance

Every HW9381633-A speed reducer supplied by TOPNLMS is covered by a 12-month warranty from the date of shipment. This warranty covers manufacturing defects and functional failures under normal operating conditions consistent with the Yaskawa HP20/HP20D application specification.

Prior to dispatch, each unit undergoes outgoing quality inspection including visual examination of the housing, output flange, and mounting surfaces, as well as a manual rotation check to confirm smooth operation and absence of abnormal resistance or play. Units that do not pass inspection are not shipped.

In the event of a warranty claim, TOPNLMS will assess the returned unit and provide either a replacement or a credit, depending on the nature of the defect and the customer’s preference. Our standard response time for warranty inquiries is within 2 business days. Customers are advised to retain the original packaging and shipping documentation to facilitate any claim.

For procurement teams managing planned maintenance schedules, TOPNLMS can provide advance stock reservation and staged delivery to align with your maintenance window. We ship from Xiamen, China, with DHL Express, FedEx International Priority, and sea freight options available depending on urgency and order volume.

For technical pre-sales questions, compatibility verification, or bulk pricing inquiries, contact our team directly.