Product Overview
The N403111 / 496244-00 SDS Plus Chuck Assembly is a precision-engineered direct-fit replacement for the impact tool holder (chuck) used on SDS Plus rotary hammers built on the D25124 platform. This complete chuck assembly – also referred to as “Holder Tool,” “CHUCK SA,” or “impact chuck assembly” in parts diagrams – is the critical interface that secures SDS Plus drill bits and chisels during hammer drilling and chiseling operations.[reference:5][reference:6]
Designed for professional repair technicians and equipment maintenance specialists, this chuck assembly restores factory-spec bit retention to tools suffering from worn locking mechanisms, bit slippage, or contamination-related failures. The SDS Plus (TE-C) shank interface enables tool-free bit changes with positive locking engagement – pull the locking sleeve, insert the bit, and release.[reference:7]
Critical Note on Part Number Interchangeability: This chuck assembly is referenced under multiple OEM part numbers including N403111, 496244-00, N591846, and 584558-00.[reference:8][reference:9] All numbers reference the same SDS Plus impact chuck assembly – this listing supplies the current-spec assembly that replaces all variants.
💡 Pro Tip – Pre-Installation Diagnostic: Before replacing the chuck, test bit retention with a known-good SDS Plus bit. Insert the bit fully – you should hear a distinct click and feel positive engagement. If the bit pulls out without pressing the release collar, the internal locking mechanism has failed. Also inspect the bit shanks for wear – mushroomed or deformed shanks can damage a new chuck.[reference:10] Always remove the battery pack (cordless) or disconnect from mains power (corded) before beginning any disassembly procedure.
Diagnostic & Fitment – When to Replace
Specification Comparison
| Specification | Worn / Generic Aftermarket | FixPartHub Precision Replacement ✅ |
|---|---|---|
| Bit Retention Force | Weak or inconsistent – bits slip under load | Positive locking – OEM-spec retention |
| Locking Mechanism | Worn or contaminated – unreliable engagement | Factory-spec mechanism – consistent engagement |
| Locking Sleeve Operation | Stiff, sticky, or seized | Smooth operation – tool-free bit changes |
| Part Number Status | Generic cross-reference – uncertain compatibility | N403111 / 496244-00 / N591846 / 584558-00 – active OEM specification[reference:11] |
| Compatibility | Vague or incorrect fitment claims | D25124K / D25134 / D25144 – direct-fit guaranteed[reference:12] |
Installation & Replacement Workflow
Compatibility – Cross-Reference & OEM Part Numbers
Diagnostic Q&A
❓ Q: My SDS Plus bits keep falling out – is this a chuck problem or a bit problem?
A: Test with a known-good SDS Plus bit. If the bit locks securely, the issue is with your bits – inspect for mushroomed or deformed shanks. If the problem persists across multiple bits, the chuck’s internal locking mechanism has worn or failed – requiring replacement of the N403111 chuck assembly.[reference:15]
❓ Q: What is the correct part number for this chuck – N403111 or 496244-00?
A: Both N403111 and 496244-00 reference the same SDS Plus impact chuck assembly, along with N591846 and 584558-00.[reference:16][reference:17] This listing supplies the current-spec assembly that replaces all variants. All are functionally identical and fully interchangeable.
❓ Q: Will this chuck fit my D25124K rotary hammer?
A: Yes. This N403111 SDS Plus chuck is engineered as a direct-fit replacement for D25124K, D25134, D25144, and compatible SDS Plus rotary hammer platforms.[reference:18][reference:19] The SDS Plus (TE-C) interface is standard across this platform family.
❓ Q: What causes SDS Plus chucks to fail prematurely?
A: The most common causes are: (1) debris contamination from concrete dust entering the locking mechanism, (2) use of worn or deformed bits that damage the internal locking components, (3) lack of maintenance on the SDS Plus shank interface, and (4) normal wear of the locking balls and spring mechanism after extended use.
Safety Notes
- 🔴 Always disconnect the tool from power – remove the battery pack (cordless) or unplug from mains (corded) before beginning any chuck removal or installation procedure.
- 🧤 Wear appropriate PPE – safety glasses and cut-resistant gloves when handling chucks and drill bits.[reference:20]
- 🔧 Clean the spindle interface thoroughly before installing the new chuck – debris can prevent proper seating and cause premature wear.
- 📐 Test bit retention before operating the tool – insert an SDS Plus bit and verify positive locking before use.[reference:21]
- ⚡ Never operate the tool with a chuck that fails to lock bits securely – this creates a dangerous projectile hazard.
- ✅ Lubricate SDS Plus shanks regularly with a light coat of grease to reduce wear on the chuck’s internal locking components.
A: Insert a known-good SDS Plus bit into the chuck. You should hear a distinct click and feel positive engagement. If the bit pulls out without pressing the release collar, or if there is excessive lateral play, the chuck’s internal locking mechanism has failed. Additionally, if the locking sleeve is stiff or stuck, the chuck is contaminated or worn and requires replacement with an N403111 assembly.
A: Yes. This N403111 SDS Plus chuck is engineered as a direct-fit replacement for D25124K, D25134, D25144, and compatible SDS Plus rotary hammer platforms.
A: SDS Plus (TE-C) chucks are designed for lighter-duty rotary hammers up to approximately 30mm drilling capacity, featuring a 10mm shank diameter with two open grooves and two closed grooves. SDS Max chucks are for heavier-duty hammers with larger drilling capacity, featuring an 18mm shank diameter. This chuck is SDS Plus (TE-C) specification – verify your tool’s shank type before ordering.
