# Trip hammer: wiper cam pressing the tail of a first-order helve

> How does a trip hammer work?

- Category: Mechanisms › Cams
- Kind: Hardware
- Basis: Xem Studio design following Brown No. 353 (1868)
- Page: https://xemstudio.com/objects/trip-hammer-mechanism/ · JSON: https://xemstudio.com/api/geometry?object=trip-hammer-mechanism · Plain text: https://xemstudio.com/objects/trip-hammer-mechanism/sheet.txt
- License: dimension sheet CC BY 4.0 (Xem Studio); files Xem Studio Design License (free to use and sell from, not to redistribute as files: https://xemstudio.com/license/)
- Use in every chat: add https://xemstudio.com/mcp as a connector (https://xemstudio.com/use-with-ai/)

**Exact dimensions.** True size, with no printing tolerance added.

## Notes

- A shaft carrying wiper cams turns above the tail of the hammer helve: each lobe presses the tail down, the head at the other end of the lever rises, and when the lobe slips off the tail the head falls on the anvil. Two lobes give two blows per turn.
- First-order lever (fulcrum between cam and head): tail 80 mm, head 120 mm, so the head rises 1.5 × the cam's lift. Drawn with the helve at rest on the anvil and a lobe tip just touching the tail (contact only), ready to press.
- Brown's No. 353 (tilt hammer with the helve as a first-order lever, modified from No. 72, where it is a third-order lever).
- Parts (each has its own page): wiper-cam-2-lobe-r12-r24-b8, trip-hammer-helve-200x12, hammer-head-24x24x40, anvil-block-30x30x20, pivot-post-16x20x30-fork, linear-shafts-h6, dowel-pins-metric.
- Brown's movement No. 353 (1868) shows it; this model is a Xem Studio design following his figure, every part at true size.

## Sizes

| parameter | value |
|---|---|
| helve | 200 mm, pivot at 80 from the tail |
| cam | 2 lobes, lift 12 mm |
| head lift | 18 mm per blow |
| blows per turn | 2 |

## Where the files are

- Henry T. Brown (1868, public domain): [Five Hundred and Seven Mechanical Movements — scan on archive.org](https://archive.org/details/fivehundredseven00browiala) — web — Publisher's page; dimensions are facts
- 507movements.com: [Brown's movement No. 353: figure, his text and an animation](https://507movements.com/mm_353.html) — web — Publisher's page; dimensions are facts

## Free STEP/STL (1 parts, Xem Studio Design License, Xem Studio)

Index: https://xemstudio.com/files/hardware/trip-hammer-mechanism/index.json · license: https://xemstudio.com/files/hardware/trip-hammer-mechanism/LICENSE.md

- trip-hammer-mechanism-assembly: [STEP](https://xemstudio.com/files/hardware/trip-hammer-mechanism/trip-hammer-mechanism-assembly.step) · [STL](https://xemstudio.com/files/hardware/trip-hammer-mechanism/trip-hammer-mechanism-assembly.stl) — Assembled mechanism, all parts placed at one pose (STEP keeps each part separate)

## Questions

**How does a trip hammer work?**

A shaft carrying wiper cams turns above the tail of the hammer helve: each lobe presses the tail down, the head at the other end of the lever rises, and when the lobe slips off the tail the head falls on the anvil. Two lobes give two blows per turn.

## Fits with

- [Two-lobed wiper cam, base R12, tip R24, 10 thick, Ø8 bore](https://xemstudio.com/objects/wiper-cam-2-lobe-r12-r24-b8/)
- [Trip-hammer helve 200 × 12 × 8, Ø5 pivot 80 mm from the tail](https://xemstudio.com/objects/trip-hammer-helve-200x12/)
- [Hammer head 24 × 24 × 40 with a 12 × 8 helve socket](https://xemstudio.com/objects/hammer-head-24x24x40/)
- [Anvil block 30 × 30 × 20](https://xemstudio.com/objects/anvil-block-30x30x20/)
- [Pivot post 16 × 20 × 30 with a 12.1 mm fork and Ø5 pin hole](https://xemstudio.com/objects/pivot-post-16x20x30-fork/)
- [Linear shafts Ø3 to Ø25 mm (h6), 100 to 1000 mm long](https://xemstudio.com/objects/linear-shafts-h6/)
- [Dowel pins, 2–6 mm (ISO 2338 / DIN 6325)](https://xemstudio.com/objects/dowel-pins-metric/)