Retractable dog leashes are a great idea. Or maybe they’re not. Opinions are divided. What we can say for sure is that these are clever devices with certain shortcomings, some of which have been addressed by a number of innovations over the years. One glaring omission is the lack of progressive brakes. Let’s fix that!
How retractable leashes work
Most designs comprise a plastic case with a spring-loaded reel inside. The reel lets out string/tape when pulled, and auto-retracts when there is some slack. The reel can be locked by pressing a button.
Features that make them better
- Well-adjusted spring tension sets good quality units apart, ensuring easy extension and smooth retraction.
- Using tape instead of string helps make the leash safer because tape is superior in terms of visibility to pedestrians and cyclists.
- Specially shaped anti-twist spout helps keep the tape neat and tangle-free.
What’s missing
An important feature that’s missing from most retractable leashes is progressive braking. Typical designs have a mechanism where pressing the lock button stops the reel abruptly. This results in sudden jerks that could hurt the dog.
Upon studying a generic product, I found a plastic cogwheel and a stopper that jams between the teeth and prevents rotation. There are no brake pads of any kind, or anything that could slow down rotation gradually and/or give the dog an auditory or tactile warning of imminent leash stoppage.
[Please forgive my lousy 3D modelling]
All the models I’ve tried behave in exactly the same way, so, although I haven’t taken them apart, it would be fair to assume that they use the same braking mechanism.
This strikes me as an inadequate design, and I would speculate that this is one of the main reasons why many people give up on retractable leashes altogether. Lack of an ability to perform a safe stop is powerful deal-breaker material.
The idea
I suggest making a retractable leash where the reel can be slowed down gradually, as well as rigidly locked (as with current designs).
What already exists
Related ideas
FIDA offers an AutoBrake leash that works like a car seatbelt, halting line extension when a sudden movement is detected. This prevents the dog from picking up speed and experiencing a powerful jerk when reaching the end of the line (or when the lock button is pressed). It is a good safety feature, but does not give the user enough control over leash extension to gently change the dog’s pace in everyday situations. Besides, the safety benefits of this design are offset by its patent status, which means not all dogs can have one.
Similar ideas
Of course, someone has already thought of soft brakes, too. What’s surprising is that something so obvious remains so rare.
A company called ALPHA Leash makes a retractable leash with Gentle Stop Technology. You can head to their website right now and order one of their leashes.
Regrettably, it is a patented product, and while the team at ALPHA Leash have done a great job developing it, their manufacturing capacity appears to be limited and unable to satisfy the global demand. If we want all dogs to be able to enjoy smooth and safe retractable leashes, we need alternative, patent-free designs.
Possible designs
External friction strip
The simplest option. Install a strip of high-friction material on the outside of the case, and make guides that would keep the tape aligned with the friction strip. When the user lifts and tilts the leash in a particular way, the tape will rub against the friction strip. The braking power will be relatively low – not enough to stop a charging dog, but enough to tell a well-behaved dog to slow down. This is a cheap and simple (albeit not very elegant) solution that should cover many of the use cases.
*Update: I tested this in controlled conditions – it totally works! Just angling the case upwards creates a decent amount of friction. Next, need to devise the guides to prevent the tape from slipping off to the side.
Pros: simple and cheap, can be sold as an add-on that can be glued onto existing leashes
Cons: low braking power, doesn’t look elegant, requires some skill to operate reliably
Internal brake acting on the tape
Add an extra button or lever that would squeeze the tape between two pieces of high-friction material (material needs to be selected carefully so as not to put excessive wear on the tape).
Pros: relatively simple
Cons: limited braking power, puts wear on the tape
Internal brake acting on the reel
Add brake pads that would act on the reel (may need to extend the smooth part of the reel, i.e. make sure the diameter of the reel is more than the diameter of the toothed part, so there’s space for the brake pads). Braking action can be either integrated with the lock button (push to brake, push more to lock), or implemented as a separate button.
Pros: strong effective braking
Cons: mechanism may be more complex
Internal brake acting on the axle
For a more sturdy premium brake, we could use a band brake system akin to that found on some bicycles (which used to be especially common in Japan).
Pros: good braking performance, durable
Cons: heavier, more complex, more expensive
Damper spring
Retain the rigid braking mechanism, but add a damper spring akin to the springs that can be found on the clutch disc of a manual transmission. In automotive context, these springs absorb and smooth out sudden torque changes and vibrations, reducing drivetrain shock and making gear engagement smoother. In a retractable leash, the damper spring will likewise smooth out sudden jerks caused by locking the reel.
NB: the lock button will need to be reworked to accommodate the movement in the locked state.
Pros: works automatically without any extra actions by the user
Cons: “passive” feature that does not give control to the user
What’s in it for the company?
- A good product that is differentiated from the competition and satisfies a real need is likely to sell well.
- A massive reputation boost that comes from demonstrated evidence of the company actually caring about dogs (most companies say it, but do they really?)
Next steps
If anyone is interested in making this product, I can help model the details.
PS: Oh, and please don’t patent it. Applying for a patent is the default pathway for many products and startups, and something we take for granted, but let’s evaluate this critically.
- Remember the reputation boost I mentioned earlier? Patenting the product will undo most of that by introducing the discrepancy between the company’s claimed love for dogs and the act of preventing most dogs in the world from enjoying the safety benefits of your design. And since major part of your product’s appeal is the fact that you care, this is a big deal.
- Not patenting this product most likely won’t hurt the company. The market is saturated with “classic” retractable leashes, and is unlikely to move fast to adopt this feature, precisely because they don’t care. While they’re busy mass-producing unsafe inferior products, you have time to carve a niche for yourself, and maintain it by emphasising quality and thoughtfulness (even after the market eventually makes this feature mainstream).
“Care” is something you can’t patent, but it is surprisingly easy to be sufficiently exclusive in this niche, because most competitors simply don’t.
Submitted by: Ilia Leikin
Hashtags: #Dogs #Pets #RetractableLeash
Looking for: a company or a startup team to build the product
I can: model, make and test prototypes
Status: prototyping in progress
