Sahib Virdee

Trailer Hitch

May 2025 to July 2025

A fabricated trailer hitch system for SARIT electric three-wheelers, designed so the research fleet could tow cargo trailers without major frame modification.

[sarit hitch final with wike trailer] — Final Wike trailer hitch installed on the orange SARIT; the design had to clear the frame while allowing the trailer to articulate through turns.

Quick Read

Designed a new hitch after an earlier design had tilt and documentation issues.
Built a SolidWorks model of the Wike trailer from physical measurements.
Compared pintle, lunette, and ball-mount hitch options.
Used DFM feedback from the machine shop to revise the geometry.
Created BOMs, FEA checks, fabrication drawings, and supplier references.
Machined square tube parts, waterjet bracket plates, printed drill jigs, and installed the final assembly.

Need

The SARIT fleet was being explored as a last-mile delivery platform.

To test that properly, the vehicle needed a trailer hitch that could tow lightweight cargo trailers without permanently redesigning the SARIT frame.

A previous hitch existed, but it had a nose-down tilt issue and was not documented well enough to reproduce easily.

Wike Hitch

The first trailer was a Wike cargo trailer rated for about 150 lb / 70 kg.

No manufacturer CAD was available, so I measured the physical trailer and built a SolidWorks model to use as the design reference.

The hitch went through four main versions:

v1 compared hitch types and established the ball-mount direction.
v2 added DFM changes and early FEA.
v3 developed the full BOM with part numbers, materials, masses, and supplier references.
v4 changed the SARIT-side bracket to 6061 aluminum to reduce weight and avoid galvanic corrosion against the SARIT frame.

Fabrication

The fabrication week was July 14 to 18, 2025.

I machined the square tube components on the mill at the Bergeron machine shop and cut steel bracket plates on the water jet.

Drilling into the SARIT frame needed a 3D-printed drill jig. I also printed nut carriers because some fasteners had to be held inside hollow aluminum frame sections where a wrench could not reach.

[sarit hitch drill jig] — Printed drill jig used to locate mounting holes on the SARIT frame; this was needed because the frame geometry was not easy to mark accurately by hand.

[sarit hitch nut carriers] — Nut carriers for holding fasteners inside the hollow frame, solving an access problem that only showed up during physical test fitting.

Impact Hitch

After the Wike hitch, the team acquired a MotoAlliance Impact trailer rated for about 1,500 lb.

The second hitch was faster because the workflow was already established: measure, model, simulate, review, build.

The scale changed the design:

Thicker tube walls.
Larger fasteners, moving from 1/4 in to 3/8 in.
2 in tow ball / receiver hardware.
Heavier trailer geometry and higher load assumptions.

Outcome

Both hitches were completed and deployed.

By early 2026, the orange SARIT had a functional hitch and five assembled Wike trailers were staged in the Bergeron courtyard.

What I Would Improve Now

I would document the physical installation steps more thoroughly, especially the fastener access problems inside the frame.

The nut carriers were a useful fix, but they were discovered late. I would now treat wrench access and installation sequence as part of the CAD review, not something to solve after fabrication.