Pushchair emergency brake
This project provides an adaptation to a pushchair such that it will not roll away if inadvertently released. It therefore provides safety.
The Challenge
The client has a new baby and plans to take the child for walks in an existing pushchair. However due to a medical condition, she may become suddenly incapacitated and accidentally release the pushchair. This would be dangerous if the pushchair were to roll away.
The challenge was to add a brake feature to the existing pushchair that would lock the wheels in case of release. Such solutions do exist commercially but not after-market for this model of pushchair.
Parts had to be designed to clip or clamp to the existing pushchair frame without drilling, welding, screwing etc. Without access to metal machine tools, principle material would need to be hardwood with any metal or plastic parts adapted from hardware available in DIY stores.
Because the pushchair was soon to be in regular use, access for measurements and developing the design was limited.
The solution
It was found that commercial plastic clips designed for 22mm heating pipes were ideal for clipping supports and brackets to the pushchair frame.
With wooden backets clipped on and cross-braced, a pivoting handle assembly was designed and fitted using 8mm furniture bolts as pivots. The handle would be lifted and held against the push bar during normal operation but it would drop if released, applying the brake.
For the wheel brakes, an attempt to design spring-loaded brake shoes, that would rub against the tyres, was unsuccessful. After identifying springs and metal parts to serve as brake shoes, it was found that the brake release effort at the handle would be too high for the client to hold comfortably. It was therefore decided to utilise the pushchair’s existing pedal-operated parking brake. This is a pin-in-hole type of brake and initially not favoured, but it was accepted after finding that this type is utilised in commercial auto-stop designs.
The torsion spring and arm were taken from a commercial rodent trap and found to have enough force to push down the brake pedal. Plastic rollers fitted to the spring arm made it more efficient. The handle was connected to pedal via a length of steel cable, with screw length adjustment. A guided Bowden cable would have been neater, but the extra friction was unwanted and access to the pushchair for experimental fitting and adjusting was limited.
The wooden parts were finished in waterproof black stain to blend with the existing pushchair frame colour.
The benefit
The client is now able to take her child for walks without fear of the pushchair rolling away if she is forced suddenly to release it.
