This document is the technical manual for the DT Swiss Ratchet LN rear hub, version V2021.06, providing detailed information for both end-users and dealers on its maintenance, spare parts, and technical data.
Function Description:
The DT Swiss Ratchet LN is a rear hub system designed for bicycles, featuring a Ratchet LN freewheel mechanism. This system is responsible for transferring power from the pedals to the rear wheel, allowing the wheel to freewheel when the rider stops pedaling. The manual details the complete service procedure for this rear hub, including disassembly, cleaning, inspection, and reassembly of its various components such as end caps, ball bearings, freewheel body, ratchets, springs, and the ring nut. Proper maintenance ensures the smooth and efficient operation of the freewheel system and the overall hub.
Important Technical Specifications:
While specific numerical technical specifications like weight or dimensions are not explicitly listed in the provided pages, the manual emphasizes the use of specific DT Swiss universal grease and DT Swiss special grease for lubrication. It also specifies the use of particular tools: a tool for the ring nut (Article number: HXTXXX00N5027S) and an installation cylinder Ø15 / 28 x 40 mm (Article number: HXTXXX00N5042S). The manual highlights the importance of the spacer's length, noting that if it's shorter than 15.4 mm, it must be replaced to prevent issues like a blocked freewheel. The design of the product is valid as of 07.06.21, and all items are subject to technical changes.
Usage Features:
The Ratchet LN rear hub is designed for integration into a bicycle wheel. Its primary usage feature is its freewheel mechanism, which allows for coasting without pedaling. The manual implicitly covers usage by detailing how to maintain the hub to ensure its proper function. This includes ensuring the freewheel engages correctly and rotates smoothly without stiffness or noise. The manual also touches upon the subjective perception of freewheel sound, noting that the amount of grease between the ratchets can influence whether the sound is loud or quiet, with less grease leading to a louder sound but potentially higher wear.
Maintenance Features:
The manual is primarily a maintenance guide, offering comprehensive instructions for servicing the Ratchet LN rear hub. Key maintenance features include:
- Disassembly: Step-by-step instructions for removing end caps, the freewheel body, freewheel system components (ratchets, springs, spacer), the ring nut, and both drive-side and non-drive-side ball bearings.
- Cleaning and Inspection: Emphasizes thorough cleaning of all hub parts, including complete removal of old grease. Detailed checks for wear on ratchets (flattened edges, uneven wear) and internal teeth of the freewheel body (loss of black surface, burrs, material removal) are crucial for identifying parts that need replacement.
- Lubrication: Specific instructions for greasing bearing seats, ring nut threads, ratchets, and freewheel body teeth with DT Swiss universal grease and DT Swiss special grease. A critical safety warning highlights the risk of injury due to limited freewheel function if too much grease is applied to the ratchets, recommending only a thin, even layer of the red DT Swiss special grease.
- Reassembly: Detailed steps for mounting ball bearings (drive-side and non-drive-side), the ring nut, assembling the freewheel system (springs, ratchets, spacer), and mounting the freewheel body and end caps. Instructions include proper orientation of components (e.g., colored side of bearing outwards) and tightening procedures (e.g., turning the ring nut counterclockwise to loosen, clockwise to screw on, then tightening by hand).
- Troubleshooting: A dedicated section addresses common issues such as a blocked freewheel, freewheel not engaging/slipping, axial play in the hub, stiff hub rotation, and hub noise. It provides potential reasons for these issues (e.g., forgotten spacer, incorrect grease, worn parts, improper bearing installation) and corresponding solutions (e.g., checking assembly, replacing worn parts, cleaning and regreasing).
- Tooling: Specifies the required special tools for damage-free mounting and dismounting, emphasizing the use of grind clamping jaws, aluminum clamping jaws, or special tools to clamp adapters to prevent damage. It also stresses the importance of keeping tools in perfect condition and properly stored.
- Environmental Protection: Advises adherence to statutory regulations for waste disposal, particularly for carbon, lubricants, cleaners, and other fluids, promoting environmentally compatible disposal methods.
The manual is structured to guide users through each step, often accompanied by visual aids (images) to clarify the process. It also includes important safety warnings (DANGER, CAUTION, NOTICE) to highlight potential risks to the user or property.
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