A national Light Rail Transit (LRT) depot needed three specialized systems to maintain and paint rail bogies — the wheel-and-axle assemblies beneath each train car. Equipment like this doesn't exist as an off-the-shelf commercial product; SRT engineered and fabricated all three as one integrated solution, built around the product's actual geometry and the depot's rail infrastructure.
Engineering Challenge
The project documents establish three specific constraints that shaped this engineering problem: first, a defined product to design around — a target bogie at approximately 6.5 tons with a fixed, known geometry. Second, a painting process with an inherent air-quality and safety dimension — manual spray-gun application generates overspray and solvent-laden air that must be controlled continuously, not incidentally. Third, a fixed infrastructure constraint — the depot's track gauge (1,435mm, standard gauge) that any turntable or lifter had to match precisely, leaving no tolerance for a generic design.
Engineering Process
SRT's approach treated this as three coupled sub-problems sharing one product interface (the bogie), rather than three unrelated pieces of equipment. For the painting booth, the governing engineering question was containment and airflow. For the lifter, it was load path and redundancy. For the turntables, it was positional precision under manual operation. The engineering calculation package documents a structured verification process — design criteria established first, followed by component-level technical specification, followed by structural/mechanical verification of the load-bearing elements.
Engineering Solution
Mechanical Engineering
A wet-type painting booth (water-curtain: water screen → eliminator → scrubber), sized at approximately 7.2m × 5.5m × 2.6m, with an 85% primary fresh-air filter and a sub-0.4 m/s supply air velocity. The bogie lifter uses a multi-point, synchronized screw-jack system with a 10-ton design capacity against an actual load of approximately 6.5 tons, a traveling-nut mechanism with dust-proof bellows. The turntables are fabricated in two capacity classes (30-ton and 10-ton) with a 4-meter table diameter, a center-post-and-guide-roller arrangement, and a four-point locking device at each 90°.
Structural Engineering
The turntable and lifter both carry the bogie's full weight through a defined load path. The engineering calculation package documents structural verification of these load-bearing elements as a formal step in the design process — the specific verification results and safety margins are part of SRT's internal engineering documentation and are not disclosed here, consistent with client project data confidentiality.
Process Engineering
The painting booth's water circulation system (water screen, eliminator, scrubber, and dual circulation pumps) functions as a continuous industrial process system, not a static enclosure — this is process equipment engineering (fluid circulation, filtration, air handling) applied inside a mechanical structure.
Electrical Integration
The lifter's drive system operates on a standard three-phase industrial supply (380V, 50Hz), integrated with the equipment's control panel and safety devices — placing the electrical scope within standard Indonesian industrial power practice.
Utility Integration & Industrial Design
The painting booth integrates water circulation, forced-air supply and exhaust, and filtration in one coordinated system. Equipment access is built into the layout rather than added afterward: the booth's main doors are sized for full bogie access from both front and rear, and the turntable's every-90° locking arrangement is itself an industrial-design decision — defining exactly how many working orientations are available.
Engineering Highlights
Custom-engineered around a single defined product, not adapted from general-purpose equipment
Wet-type overspray capture chosen deliberately for continuous manual spray operation
Redundant circulation pumping (standby configuration) in the booth's water system
Multi-point synchronized lifting rather than a single-point hoist
Lifting system design capacity carries genuine margin above actual product weight
Dust-proof bellows protection on the lifting mechanism, suited to a depot environment
Dual-capacity turntable design (30-ton & 10-ton) tailored to different workflow points
Four-point, every-90° locking giving defined, repeatable working orientations
Track gauge precision (1,435mm) maintained across both turntables for rail integration
Front-and-rear bogie access built into booth door sizing, avoiding mid-process repositioning
Filtered fresh-air supply (85% primary filter efficiency) integrated into the air-handling design
Controlled supply air velocity specifically tuned to avoid disturbing manual spray application
Three separate utility systems engineered as one coordinated process
Standard industrial three-phase power integration (380V/50Hz) for the lifter drive system
Structured, staged engineering process applied consistently across all three systems
Engineering Value Delivered
- Purpose-fit equipment — sized and configured around the actual product and facility constraint, rather than a generic solution adapted after the fact.
- Safer painting operation — overspray containment and filtered air supply engineered as a continuous process, addressing operator air-quality exposure directly.
- Operational redundancy — standby pumping means the equipment's core safety function doesn't depend on a single component staying online.
- Maintainability by design — dust-proof bellows and full front/rear access reduce the maintenance burden over the equipment's service life.
- Workflow-level engineering — three systems specified and arranged as one depot workflow, not isolated equipment specifications.
- Engineering flexibility across duty classes — two turntable capacities for two distinct operational points, not one oversized universal solution.
Engineering Capability Demonstrated
| Capability | Demonstrated in This Project |
|---|---|
| Mechanical Engineering | Yes — booth, lifter, and turntable mechanical design |
| Structural Engineering | Yes — load-bearing verification for lifter and turntable structures |
| Industrial Design | Yes — access, orientation, and workflow-level layout decisions |
| Process Engineering | Yes — water circulation, filtration, and air-handling system design |
| Electrical Integration | Yes — three-phase drive and control integration |
| Fabrication | Represented in the specification package as the intended scope |
| Installation | Represented in the specification package as the intended scope |
| Testing & Commissioning | Represented in the specification package as the intended scope |
| Project Management | Yes — evidenced by the formal document control and revision structure |
| Engineering Documentation | Yes — general arrangement drawing and structured calculation package |