What’s in Your Clothes Dryer (Besides Clothes)

Clothes dryers have been around for decades and show no sign of decreasing in number. They’re handy for buyers and cheap to make for distributors. Here’s a little information about what makes these things tick.

Every dryer has a rotating tumbler in which the wet clothes are held. Along with this it contains a gas powered heater that heats up the air that is pushed through the wet clothes as they tumble, which in turn heats up the water contained in the clothes as well as the clothes themselves. Finally, each dryer has an exhaust vent through which the water is released in the form of steam. Generally the exhaust vent tunnels not only out of the dryer but out of the house entirely.

dryer2Let’s think for a second about air circulation. You may have noticed that warm, moist air leaves your dryer through a hole in the back of the appliance which is then hooked up to a pipe or a vent. Did you ever wonder where the air actually enters the dryer? It enters through a large hole in the front of the dryer and is sucked past the heating element and into the tumbler. It then enters the door and is directed through the lint screen, passes through a duct in the front of a the dryer, and is forced into the duct leading out the back of the dryer by a fan.

Ok, how about the dryer’s ability to spin your clothes around? If you open up a dryer, you might initially be surprised that it lacks any gears on the tumbler. It turns out that the tumbler is actually just one giant gear (or pulley), and the motor drives a tiny pulley. The ratio between the larger tumbler diameter and the tiny motor pulley diameter allow for gears to be unnecessary.

The tumbler has a thin belt wrapped around it that is looped through the little pulley and then through the big pulley. Tension is created between the belt pulling the pulley off center and the spring that pulls it back in the opposite direction.

The same electric motor actually drives both the fan and the tumbler. The pulley for the tumbler belt is attached to one output of the motor and the fan is hooked up to the other.

There are no bearings in a dryer to help the tumbler support the weight of the load of clothing and spin smoothly. Instead, a flange that is spun by a simple bushing and bolted to the back of the tumbler.

dryer3The dryer’s controls are not electronic. When you turn a knob to start a load, a system of gears, cams, electrical contacts and motors work in synchrony to make sure your dryer functions according to your liking. Just a quick turn of the cycle switch activates a motor that turns a gear on the dial, which si then connected to a set of four cams stacked on top of each other which in turn engage one of the four contacts in the switch. Each contact has a bend in it and each bend is located at a different height inside the box. Each connected cam ups the heat a little further.