Focusing on the design, manufacturing processes, heat treatment techniques, and key quality control points for all types of standard and non-standard gears.
| Parameter | Specification |
| Spline Standard | DIN 5481 |
| Number of Teeth | 12–30, Customizable |
| Pressure Angle | 45° |
| Fit Type | Fixed Connection, Sliding Fit Available |
A Triangular Internal Spline Sleeve, also known as a serrated internal spline sleeve, is an internal spline component with a triangular tooth profile. It mates with an external spline shaft to transmit torque and provide axial positioning. With a compact design, large tooth contact area, and relatively low manufacturing cost, it is commonly used in medium- to low-load mechanical transmission systems where installation space is limited.
Compared with involute splines, triangular splines can accommodate a greater number of teeth on the same shaft diameter, providing good torsional rigidity and tooth root strength. They are particularly suitable for space-constrained, low- to medium-torque applications and assemblies requiring fine angular adjustment through multiple spline teeth. Typical applications include automotive components, agricultural machinery, drive shafts, hydraulic systems, and industrial automation equipment.
Triangular internal spline sleeves use a triangular or serrated tooth profile, with multiple spline teeth evenly distributed around the bore. Compared with involute splines, the triangular spline structure is more compact and provides relatively thicker tooth roots. More teeth can be arranged within the same outside diameter, allowing the transmitted load to be distributed across multiple tooth flanks while offering good manufacturing economy and connection rigidity.
A triangular internal spline sleeve normally mates with an external spline shaft, transmitting rotational torque through contact between multiple tooth flanks. During operation, the load is shared by several spline teeth, helping distribute the transmitted force and maintain a stable connection.
Its compact design, reliable connection, and convenient assembly make it suitable for both fixed connections and axial sliding connections, depending on the application. It can also be used in transmission structures requiring frequent assembly and disassembly or controlled axial movement.
Triangular splines transmit torque through simultaneous contact across multiple tooth flanks, providing good torsional strength. Broaching and shaping are commonly used for manufacturing, with additional finishing available according to the required accuracy. Common heat treatments include quenching and tempering, induction hardening, carburizing, and nitriding. For low-carbon alloy steels, carburizing and hardening can improve tooth surface properties. These treatments can increase surface hardness and wear resistance for different strength and service life requirements.
The main advantages of triangular internal spline sleeves include a simple structure, reliable axial positioning and assembly, relatively low manufacturing cost, and dependable power transmission. They are suitable for low- to medium-torque transmission and mechanical connection applications.
Depending on the application, materials such as 45 steel, 40Cr, 42CrMo, and stainless steel can be selected. Tooth count, dimensions, tolerance grades, and surface treatment can also be optimized to improve load capacity and operating stability.
Triangular internal spline sleeves are widely used for shaft-to-hub connections and power transmission in automotive components, drive shafts, hydraulic equipment, construction machinery, agricultural machinery, and industrial automation systems.
| Parameter | Standard Mass-Production Model (General Service) | High-Precision Custom Model (Precision Transmission) |
| Core Connection Specifications | ||
| Spline Type | 45° pressure-angle involute triangular spline | Precision triangular spline; profile optimization and fine-clearance matching available |
| Spline Standard | DIN 5481 | DIN 5481 and non-standard requirements supported |
| Number of Teeth | 12–24 standard series | Optimized according to load, service life, and installation space |
| Bore Diameter | Standard shaft diameter series with conventional tolerances | Precision control of bore diameter, tooth thickness, and fit clearance |
| Outside Diameter | Conventional wall thickness for general strength requirements | Optimized wall thickness and profile according to rigidity and installation space |
| Fit Type | Fixed connection with flank centering | Precision centering; fine-clearance sliding fit available |
| Tooth Profile & Accuracy Specifications | ||
| Accuracy Grade | DIN Grade 7 | DIN Grade 6 and higher precision grades |
| Fit Accuracy | Standard fit and flank clearance control | Precision control of flank clearance, concentricity, and fit consistency |
| Tooth Surface Quality | Broaching or shaping with standard surface finish | Sizing, honing, and precision finishing for improved surface quality and running stability |
| Materials & Manufacturing Capabilities | ||
| Material Selection | 45 Steel, 40Cr, 42CrMo, stainless steel | 42CrMo, 20CrMnTi, 20CrMo, and other high-performance alloy steels |
| Heat Treatment | Quenching and tempering, induction hardening | Controlled surface hardening and other strengthening treatments |
| Machining Processes | Broaching, shaping, and post-heat-treatment sizing | Precision shaping, honing, matched grinding, and finishing |
| Surface Treatment | Black oxide, phosphating, and standard corrosion protection | Precision corrosion protection and special surface treatments |
| Remarks | The above are standard machining parameter ranges for our triangular internal spline sleeves. Special sizes and non-standard structures can be custom-made according to your drawings or samples. For a quotation, please provide spline standard, number of teeth, bore diameter, spline length, material, accuracy requirements, and quantity. | |
High-quality blanks are forged and normalized to eliminate internal stress and stabilize material structure.
Turning, milling and hobbing/shaping are applied to form the target tooth profile with strict accuracy control.
Carburizing quenching or tempering processes to improve tooth surface hardness and core toughness.
Grinding of tooth flanks, bores and datum faces to correct deformation and enhance meshing precision.
Full-dimensional verification by gear measuring center and CMM to qualify products before release.
Professional anti-rust and protective packaging to keep products intact during storage and transit.
High-precision gear grinding delivers tooth surface roughness as low as Ra 0.4, with tight meshing, low vibration and noise for smoother equipment operation.
Premium materials matched with precise heat treatment ensure wear-resistant tooth surfaces and impact-resistant core, cutting maintenance and replacement costs.
Custom solutions for high-speed heavy load, corrosion resistance and food-grade scenarios, eliminating trial-and-error costs in product selection.
Scaled production supports tiered pricing for bulk orders with consistent quality; full-process control guarantees stable lead time and complete after-sales support.
Representative Grades: 45 Steel / C45
45 steel offers a good balance of strength, toughness, and machinability at a relatively low cost. Quenching and tempering or induction hardening can improve spline flank wear resistance. It is suitable for general machinery, agricultural equipment, and low- to medium-torque, medium-load spline connections.
Representative Grades: 40Cr, 42CrMo
40Cr and 42CrMo provide high strength, toughness, and fatigue resistance. Quenching and tempering or induction hardening can improve spline flank hardness and wear resistance. 40Cr is suitable for medium- to high-load transmission, while 42CrMo is better suited to heavy-duty and long-term operating conditions.
Representative Grades: 20CrMnTi, 20CrMo
20CrMnTi and 20CrMo develop a hard surface layer and tough core after carburizing and hardening, providing good wear resistance, fatigue resistance, and impact strength. They are suitable for automotive transmissions, heavy-duty machinery, and spline connections for continuous operation.
Representative Grade: 38CrMoAl
38CrMoAl can achieve high surface hardness, wear resistance, and dimensional stability after nitriding while retaining good core toughness. It is suitable for precision transmission systems, automation equipment, and spline connections requiring long-term dimensional accuracy.
Representative Grades: 304, 316, 420
Stainless steel offers good corrosion resistance and environmental durability. 304 and 316 are suitable for humid and corrosive environments, while 420 can achieve higher hardness and wear resistance through heat treatment. Typical applications include food, medical, chemical, and other corrosion-sensitive transmission systems.
Representative Grades: ZG45, QT450
Cast steel and ductile iron offer good castability. Cast steel provides higher load capacity, while ductile iron offers a combination of wear resistance and vibration damping. They are suitable for larger spline connections used at low speeds and under medium loads in industrial equipment.
Triangular internal spline sleeves are used for shaft connections in automotive transmission systems, construction machinery, and vehicle actuators, providing torque transmission and component positioning. Their multi-tooth load-sharing design helps distribute loads and suits operating conditions involving vibration, impact, and varying loads.
In tractors, harvesters, mining machinery, and other heavy equipment, triangular internal spline sleeves connect drive shafts and transmission components. Combined with materials such as 40Cr and 42CrMo and suitable heat treatment, they can meet the demands of higher torque, fluctuating loads, and continuous operation.
Triangular internal spline sleeves are used to connect shafts with rotating components in automation equipment, CNC machine tools, and precision machinery. Proper control of spline dimensions, tolerances, and fit accuracy helps improve assembly consistency and operating stability, especially in structures requiring repeatable assembly and precise fits.
In hydraulic pumps, hydraulic motors, and industrial power transmission equipment, triangular internal spline sleeves are commonly used to connect input and output shafts. Appropriate material selection, heat treatment, and machining accuracy can improve tooth flank wear resistance and fatigue performance for continuous-duty applications.
In gear reducers, transmission boxes, and power transmission equipment, triangular internal spline sleeves connect shafts with gears, couplings, and other rotating components. Their compact design and multi-tooth load sharing make them suitable for space-constrained systems operating at medium-low speeds and transmitting moderate torque.
In hand tools, adjustment mechanisms, and general machinery, triangular internal spline sleeves provide reliable shaft-to-sleeve connections and angular positioning. Their compact, multi-tooth design is suitable for low- to medium-torque applications where convenient assembly and disassembly are important.
Inner VCI vacuum anti-rust process fully seals tooth flanks and critical machined surfaces, effectively resisting salt spray and moisture during ocean and air freight to keep precision gears corrosion-free throughout long-distance transit.
We select cost-effective logistics channels with stable transit time and controlled costs. Full logistics tracking is available with real-time status updates to ensure reliable and punctual delivery.
All products are covered by a 1-year warranty. Quality defects caused by non-human factors are fully guaranteed, removing your procurement concerns.
Our professional technical and after-sales team is always available to respond quickly to inquiries and after-sales needs, and efficiently resolve issues during installation and operation.
We support full-parameter OEM/ODM customization based on 2D/3D drawings or physical samples, including module, tooth profile, material and heat treatment specifications. You only need to provide core gear parameters, detailed drawings or physical samples to start the customization process.
You can send physical samples to us via international courier. Upon receipt, we will complete full-dimensional measurement and parameter verification, then arrange sample production after confirming the solution, ensuring the finished product fully matches the original in installation dimensions and transmission performance.
Prototype orders usually ship within 15–25 days, subject to heat treatment and grinding scheduling. Lead time for bulk orders will be confirmed after process finalization, with stable and well-managed production schedules.
We adopt a tiered pricing policy — the larger the order quantity, the more favorable the unit price. All orders follow the same production and quality inspection standards with strict accuracy control. Quality will never be compromised for larger order volumes.
We can include dimensional inspection reports, hardness test records and material certificates with each shipment. For high-precision key projects, professional inspection data from CMM and gear measuring centers is also available.
All products come with a 1-year warranty covering material defects and manufacturing quality issues under normal use. We also have a professional technical team to provide full-process consultation and selection support.
Spur gears feature a simple structure and no axial load, ideal for medium-low speed general transmission with higher cost-effectiveness. Helical gears run smoother with lower noise and higher load capacity, suitable for high-speed heavy-duty applications. We can recommend the optimal solution based on your actual requirements.
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info@destinytrans.com 
