Expanding Soccer Goal: Ratchet Mechanism from 6×12 to 7×16 ft
A goal that grows with a crank — telescoping posts and crossbar driven by an internal ratchet, modelled and animated to show the mechanism working inside the tube.
A goal that starts small and expands as you crank a handle — from 6×12 ft to 7×16 ft — with the mechanism hidden inside the posts.
The problem
Telescoping structures are easy to draw and hard to make work:
- Three members extend at once — two vertical posts and a longer crossbar — and they have to arrive at their end positions together, or the goal racks into a parallelogram.
- A goal takes shock loads. Whatever holds the extension has to resist a ball strike, not just gravity.
- The mechanism lives inside the tube, so every component has to fit within the post’s inner diameter and still be assemblable.
- The client needed to sell the idea. The deliverable included animation showing the expansion and a cutaway of the internal mechanism — the mechanism had to be understandable to non-engineers.
The approach
- Ratchet as the holding element, giving positive engagement at discrete positions instead of relying on friction clamps that slip under impact.
- Extension geometry coordinated across members so the frame stays square through the range rather than only at the two end states.
- Sections sized for the inner tube, treating the post bore as the hard boundary and designing the drive within it.
- Animation as an engineering output. Showing the internal motion forced the mechanism to be resolved completely — you cannot animate a mechanism that does not work.
The result
A full 3D model with expansion animation and internal cutaway views, quoted and delivered as separate design and animation scopes at the client’s request.
Where this applies
Telescoping and expanding structures: goals, stands, gates, frames. Coordinated extension and positive locking are the two things that decide whether it feels like a product or a prototype.
I design mechanisms and produce the animations that explain them to investors and buyers. Request a quote or see all services.