The Invention
The patent, US437937A, granted to Humphrey H. Reynolds of Detroit, Michigan, on October 7, 1890, is for an improved safety gate system for drawbridges. The invention is designed to automatically lower a safety gate on the bridge’s approach before the draw-section opens and to automatically raise it as the draw-section closes. This system improves the safety of both pedestrians and vehicles.
Key Features of the System:
- Automatic Gate Operation: The system links the movement of the safety gate directly to the drawbridge’s swing section.
- Gate and Uprights: The safety gate itself consists of a horizontal bar (M) that is designed to rise and fall between two vertical uprights (L L) on the bridge’s approach.
- Cable and Drum Mechanism: The gate is raised and lowered by a system of cables (
t) that run over sheaves and are wound onto a drum (H). This drum is mounted on a shaft with a gear-wheel (I). - Sliding Rack and Bolt: The crucial innovation is a sliding frame with a curved rack (K) that is secured to the underside of the swinging bridge section.
- When the bridge closes, this rack engages with the gear-wheel on the drum, causing the drum to wind the cables and raise the gate.
- The sliding frame also has a lock-bolt (
d) that automatically engages with springs on the approach as the bridge swings into place, securing the bridge section.
- User Control: A lever, inserted into a head (G) on the bridge, allows the operator to manually slide the rack and bolt.
- To open the bridge, the operator uses the lever to slide the bolt out of its locking springs and simultaneously pull the rack away from the gear-wheel. This releases the gear, allowing the gate to fall due to its own weight.
- To close the bridge, the operator slides the rack back into position. As the bridge swings closed, the rack re-engages the gear-wheel, raises the gate, and the bolt automatically re-locks the bridge section.
Significance of the Invention and Inventor
Humphrey H. Reynolds’s patent for a safety gate is an excellent example of a late 19th-century inventor solving a major public safety issue with a clever mechanical system.
- Enhanced Public Safety: Drawbridges were a common feature of cities with water navigation, but they posed a significant risk to the public. People and vehicles could accidentally drive off the end of an open bridge. Reynolds’s invention provided a much-needed, reliable, and “automatic” safety system that reduced the potential for accidents.
- A Coordinated Mechanical System: The design’s strength lies in its elegant coordination of different mechanical parts. By linking the gate’s motion directly to the bridge’s, Reynolds created a fail-safe system. It eliminated the need for a separate, manual operation of the gates, which could be forgotten or delayed. The system was designed to work seamlessly and reliably with the bridge’s primary function.
- A “Common” Inventor: Humphrey H. Reynolds was likely a local inventor, as many were in the late 19th century. His patent was assigned to a partner, suggesting a collaboration to commercialize the idea. This patent shows how ingenuity was applied to solve practical problems that arose with the growth of modern infrastructure, and how even seemingly simple mechanical solutions could have a significant impact on public safety.
