If you've ever tried transferring without them, then you know that manual wheelchair wheel locks
- or brakes, as they're commonly called - are truly a life saver. After all, wheel locks keep your wheelchair
from scooting when... well... you're scooting! |
However, beyond simply holding the wheelchair
in place, wheel locks must meet your functional and ergonomic needs, where understanding wheel lock types
and lingo will assist in choosing the best technology for your transfers.
Push-to-lock brakes are the most common form of wheel locks, found on products ranging
from low- to high-end manual wheelchairs. Push-to-lock brakes work well for many because the handle engages
forward, and downward, increasing transfer clearance. In fact, some push-to-lock brakes feature a curved
handle, so when the brake is engaged, there's not a handle protruding above the seat surface at all,
allowing totally unobstructed transfers.
Functionally, pull-to-lock brakes serve as a wheel lock the same as a push-to-lock,
only the operational motion is reversed - that is, you pull to engage them. However, when pull-to-locks
are engaged, the handle protrudes upward, which can interfere with transfers. Nevertheless, pull-to-lock
brakes are commonly used on very short frame depths, where pushing the brake forward might interfere
with swing-away legrests.
Push-to-Lock Vs. Pull-to-Lock
An interesting debate in the rehab
community is when to prescribe push-to-lock versus pull-to-lock brakes? Some argue that push-to-locks
can be especially helpful to some with muscle weakness, where one can use triceps and body weight to
press forward and downward easier than pulling back on a brake. However, both engaging and disengaging
a brake takes strength, so it's arguably a moot point which direction is easier - that is, both brakes
styles require pushing and pulling. Therefore, preferences might be best based on functionality - transfer
clearance or frame length restrictions - rather than dramatic reasons of ergonomics.
For those with limited strength and grip, extension handles can be added to
both push- and pull-to-lock brakes, allowing extra leverage. Extension handles do stick up 6" or so above
the seat, so they can dramatically interfere with transfers. For this reason, extension handles are either
removable or folding (with folding proving exceptionally convenient for those with limited dexterity).
Unilateral Wheel Locks
Unilateral wheel locks, available as push or pull, allow one lever
to lock both wheels at once, an option needed by those who have the use of a single arm.
As most aggressive ultralight manual wheelchair users know, push- and pull-to-lock brakes can get in
the way during propulsion, catching one's thumbs. To eliminate any protruding parts, scissor-lock brakes
fold under the seat when not in use, leaving the handrim's full path unobstructed when propelling. To
operate scissor-lock brakes, on reaches under the seat, and folds them outward, engaging them. It is
important to note that scissor-lock brakes require increased dexterity and coordination compared to push-
and pull-to-lock brakes, so they're not suitable for some with involved disabilities.
The newest - and most costly - type of brakes are hub locks, in which the wheel is locked via a pin at
the hub rather than a conventional brake simply pressing against the tire. Of course, because hub locks
feature an absolutely positive lock - a pin penetrating a disc at the wheel's hub - there's no risk of
them ever slipping, creating absolute security. However, hub locks, which can be ordered for specific
models of new and existing wheelchairs, are very expensive at approximately $400 per set.
Grade Aids, or "hill holders," are anti-rollback mechanisms that work in conjunction with brakes
to keep the wheelchair from rolling backward when propelling up ramps and hills. For those with limited
strength and coordination, grade aids dramatically improve independence, allowing one to avoid struggling
to maintain the wheelchair's position when climbing grades by simply rotating the grade aid against the
tire to start, then propelling forward.
Wheel locks, like many other wheelchair
components, require maintenance to ensure optimal performance. Firstly, if pneumatic tires are used in
conjunction with brakes, the tire's suggested air pressure should be maintained - even a slightly deflated
tire can dramatically reduce a brake's effectiveness. Secondly, as tires wear, brakes should be readjusted,
moved proportionately closer to the tires to maintain full contact when engaged. Lastly, it's vital to
ensure the brakes' mounting hardware remains tight - brakes undergo tremendous forces, and loose mounting
hardware can permit an engaged brake to skew and lose grip under load.
Wheel locks are one
of those items that many don't think of until they really, really need to rely on them - that is, usually
in the middle of a transfer. However, choosing the right wheel lock from the start can dramatically improve
the performance, convenience, and safety of your manual wheelchair.
Published 1/08, Copyright 2008, WheelchairJunkie.com