STM - Society in motion
They are one of a kind and they are made right here in the STM shops. They play a crucial role. And they’re made of wood soaked in peanut oil.
Most métro cars around the world are equipped with either steel or graphite brake shoes. In Montréal, wooden brake shoes are used instead, as they generate less noise than steel shoes and less pollution than graphite ones.
For its new métro cars, the STM required a high level of performance of both parts and systems for reasons of safety and efficiency, and to keep maintenance costs in line. The goal is to avoid wearing out the métro cars’ steel wheels and to keep braking noise to a minimum, all at once. And only wooden brake shoes meet both requirements !
Follow us as we visit the workshop where wooden brake shoes are made.
The Montréal métro’s wooden brake shoes
Wooden brake shoes have been used by métro cars to brake ever since the métro first opened. And we’ll be using the same wooden brake shoes on our new MPM-10 cars, the exact same type. We wanted braking to be quiet, without any screeching, and without wearing out the steel wheels prematurely. Wooden brake shoes were the only solution. They make it possible to preserve our steel wheels for the full service life of a métro car, which is about forty years. So, we figure we are saving tens of thousands of dollars during that 40-year period.
The wooden brake shoe shop is here. Two people work here year-round and, three times a year, they produce some 17,000, almost 18,000 shoe brakes. The rough wood is assembled here, and after they are cut with a band-saw to shape them to fit the wheels. Once the pieces are cut, they are placed in a basket and lowered into a vat of hot peanut oil for the wood to soak up, producing less friction with the steel later on. After removing the brake shoes from the soaking vat, they are left to drip-dry for about thirty days. The next step is yet another bath, but this time in salt water to prevent mould from building up on the brake shoes.
The brake supplier for the MPM-10 métro cars has tested the wooden brake shoes in their manufacturing plant. And they also determined that, no, wooden brake shoes don’t screech. And, yes, it’s also true they don’t wear out steel wheels. What’s more, they even said it smelled nice, like an outdoor barbecue.