Surprising Things Made by Presses
Bicycle Pedals
We all remember our first time riding a bike. For me, that memory is accompanied by the memory of crashing into the bush in my front yard. Bikes are so popular, in fact, hundreds of songs have been written about riding them.
Now imagine if bikes had no pedals. You wouldn't be able to propel yourself. You wouldn't even be able to stand up off the seat. Bikes would be pretty boring, and unless you’re going downhill, they’d be pretty useless. It's funny how such a small component is so crucial to something that most of us have a strong childhood (and even adulthood) connection to.
How did bicycle pedals come to be?
The velocipede, a predecessor to the bicycle, lacked pedals but allowed a crank to be operated by means of a treadle. Pedals were initially attached to cranks connecting directly to the driven wheel - which was usually the front wheel. A good example of this is a penny-farthing, also referred to as a high wheeler. This was a type of bicycle that had a large front wheel and a much smaller rear wheel.
The safety bicycle, as it is known today, became popular in the 1880s as an alternative to the penny-farthing. This is the model that modern bikes are based on, with pedals attached to a crank that drives a sprocket. The sprocket then transmits power to the rear wheel by means of a chain.
Bicycle Pedals - What They Are & How They’re Made
Pedals consist of a spindle that threads into the end of the crank and a platform, on which the foot rests or is attached, that is free to rotate on bearings with respect to the spindle. There are several varieties of pedals, including platform, quill, and clipless pedals.
This simple bicycle component requires some advanced and precise pressing technology to assemble. Today, a common approach is to use a pneumatic toggle press or hydro-pneumatic press, depending on the pedal design. If there are bearings (lower cost pedals do not have bearings) they may need to be inserted in a separate operation from attaching the platform to the spindle. This insertion can be done with a direct acting pneumatic press. Additionally, when inserting the spindle into the platform, it’s important to maintain a precise depth, which is verified by an integrated sensor in the press.
A well designed pedal will ensure smooth operation. While assembling the pedal, considerations must be given to the amount of force applied. Excessive force could bend the spindle, which likely would result in scrap, not to mention causing you to crash into the bush in your front yard. |
