Engine Assembly Specification Example for City Buses: Drilled and Slotted
Engine Assembly Specification Example for City Buses: Drilled and Slotted
This is a worked specification for engine assembly in a drilled and slotted programme. It is the document we would send a buyer who asks what exactly they are getting: the material, the dimensions that are actually controlled, the finish, and the checks that happen before anything is packed.
The drilled and slotted version exists because the duty cycle on city buses is not the same as on a showroom vehicle. Where the two are specified identically, something fails later — usually lead time that slipped twice before bulk started.

Example specification
| Item | Engine Assembly |
|---|---|
| Application | City Buses |
| Version | Drilled and Slotted |
| Base material | ABS Plastic |
| Controlled dimensions | 5 key dimensions, recorded per lot |
| Tolerance band | ±0.2 mm |
| Finish | painted |
| MOQ | 200 pieces per specification |
| Sampling | 7 working days, 3 days per revision |
| Compliance | E-mark |
How the example is built up
- Start from the duty cycle, not from the catalogue photograph.
- Fix the base material in writing — ABS Plastic, in this example.
- List the dimensions that are actually controlled and the tolerance on each.
- Name the finish and what it has to survive.
- State the inspection level and who pays when a lot fails.

Processes involved
- injection moulding
- electroplating
- gravity casting
- laser cutting
- assembly line testing
- robot welding
Where this example applies
Programmes that run drilled and slotted most often specify this build for city buses. Related applications include utility trailers, courier fleets, aftermarket retail, workshop replacements, agricultural trailers.
Checks before packing
- Dimensional report against the approved drawing.
- AQL 2.5 sampling on the finished lot.
- Finish inspection under agreed lighting.
- Carton drop test on the first lot of a new packing specification.
Questions buyers ask
What testing is included?
Standard lots ship with dimensional and hardness reports. E-mark documentation is issued with the shipment when your market requires it.
Do you handle mixed containers?
Yes. Most programmes consolidate several part numbers into one container to keep freight sensible at 200 pieces per line.
Can the specification be held on file?
Yes. Once approved, the specification is recorded against your part number so a reorder reproduces the E-mark-compliant build instead of a fresh interpretation.
What is the minimum order quantity?
The standard MOQ is 200 pieces per specification. Mixed sizes inside one shipment are accepted once the total reaches that figure.
Tell us the model, the fitment and the quantity and we will hold a production slot for you.



