Spring-Loaded Drum Drive Design

About the project

. Project Overview We are developing a compact mechanical drive system for a rotating drum used in food-processing equipment. We are looking for an experienced mechanical design engineer to design a spring-loaded, mechanically powered drive that can rotate the drum at low speed for a defined operating cycle without relying on a conventional continuously running electric motor. 2. Preliminary Requirements • Maximum drum/load: approximately 25 kg. • Target drum speed: approximately 6–10 RPM. • Required operating duration: approximately 15 minutes per cycle. • Drive concept: spring-powered / spring-loaded mechanical mechanism. • The spring must be rechargeable/resettable after each cycle. • The mechanism should provide controlled and reasonably consistent rotational speed throughout the cycle. • Compact construction suitable for a small food-processing machine. • Drive components should be located outside the food-contact area wherever practical. • Food-contact/exposed components should be suitable for hygienic food-equipment construction, preferably stainless steel where applicable. • Design should prioritize manufacturability, reliability, simplicity and low cost. 3. Engineering Scope The selected engineer is expected to develop the mechanism from first principles and perform the required engineering calculations, including: • Required continuous and peak driving torque. • Torque required to accelerate the drum/load. • Spring energy requirement for the complete operating cycle. • Spring selection and torque-versus-deflection analysis. • Gear ratio or other transmission arrangement. • Expected RPM throughout the spring discharge cycle. • Speed regulation/governor mechanism if required. • Shaft, key/coupling and bearing sizing. • Spring fatigue life and safety factor. • Structural loads and critical component stresses. • Charging/reset mechanism for the spring. • Mechanical stops, over-speed protection and other necessary safety features. 4. Design Objective The objective is not merely to produce a CAD model. The final mechanism must be mechanically viable, calculationally justified and suitable for prototype manufacture. The engineer should explain the operating principle and identify any assumptions that require physical testing. 5. Required Deliverables • Concept alternatives, preferably 2–3 where appropriate. • Recommended mechanism with engineering rationale. • Complete 3D CAD assembly. • Individual component CAD files. • STEP export of the complete assembly. • 2D manufacturing drawings with dimensions and tolerances. • Spring specification and calculations. • Gear/transmission calculations. • Shaft and bearing calculations. • Bill of Materials (BOM). • Exploded assembly view. • Assembly instructions. • Manufacturing recommendations. • Prototype recommendations and critical dimensions to validate during testing. 6. Preferred CAD Software SolidWorks, Autodesk Inventor, Fusion 360, Creo, CATIA or another professional mechanical CAD platform. Native CAD files and STEP files must be supplied. 7. Preferred Freelancer Profile • Mechanical engineer with practical mechanism-design experience. • Strong understanding of springs, gears, shafts, bearings and torque transmission. • Experience designing prototypes or small machinery. • Ability to perform engineering calculations rather than only CAD modelling. • Experience with low-speed drives, governors or spring-powered mechanisms is highly desirable. • Experience with food-processing or hygienic equipment is an advantage. 8. Information to Be Confirmed During Design The above requirements are preliminary. The selected engineer should confirm the following before final sizing: • Actual drum diameter and effective loaded radius. • Drum orientation and axis of rotation. • Actual product/load mass and distribution. • Bearing and seal friction. • Required acceleration time. • Whether rotation must be continuous or may be intermittent. • Available installation envelope for the spring and transmission. • Maximum acceptable RPM variation during the cycle. • Number of cycles expected over the service life. • Preferred manufacturing process and target prototype cost. 9. Proposal Requirements Please include the following in your Freelancer proposal: 1. Brief explanation of your proposed mechanism. 2. Relevant previous spring-driven/mechanical-drive projects. 3. 2–3 examples of similar mechanisms you have designed. 4. CAD software you will use. 5. Estimated time to concept design. 6. Estimated time to detailed design and drawings. 7. Fixed-price or milestone-based quotation. 8. Whether prototype/manufacturing support is available. 10. Commercial Structure Please quote separately for the following milestones: 9. Milestone 1 — Engineering concept and preliminary calculations. 10. Milestone 2 — Detailed spring/transmission design and 3D CAD. 11. Milestone 3 — Final engineering drawings, BOM and manufacturing package. 12. Optional Milestone 4 — Prototype support and design revisions after testing. 11. Important Note The 25 kg load alone is not sufficient to determine the spring size. The final spring and transmission must be sized from the actual drum geometry, effective radius, friction, acceleration requirements, operating speed and required cycle time. The freelancer is expected to validate these parameters before finalizing the design. 12. Project Outcome The final outcome should be a practical, manufacturable spring-loaded drive mechanism capable of rotating the specified drum at approximately 6–10 RPM for approximately 15 minutes per cycle, with a clear engineering basis for spring sizing, torque transmission, speed control, component selection and expected service life.

Skills required