There are two types of clothes dryers one is gas the other is electric. The gas dryer is half gas and half electric, the gas is used for lighting a flame to create the heat to dry the clothes, the electric is used to operate the motor, timer, ignitor, coil kit and thermostats.
The gas dryer has more working parts than the electric dryer, when there are more working parts there is a greater chance of something breaking, the gas dryer does break down more frequently than the electric dryer.
The electric dryer use 220 volts to operate the heater element only, all the other parts use 110volts. Both gas and electric dryer have some basic parts: motor, timer, belt, thermostats, and thermal fuse.
These are the functions of each part.
The motor turns the belt that is on the basket, the timer sends the desired voltage to each part for the desired time that it is set on, the thermostat contains the desired temperature and the thermal fuse shuts down the dryer if the thermostat fails.
A common problem with both gas and electric is clothes taking a very long time to dry, lint building up in the exhaust vent hose is sometimes the reason. The best way to check if the exhaust is partially blocked is to turn on the dryer. Then go outside to where the vent is, put your hand close to the vent, if there is little or no hot air coming out, your vent hose is blocked. There should be a strong flow of hot air coming out. Sometimes birds build their nest at the vent opening because of the warm air they find coming out of it. Also if the vent comes out near the ground it sometimes get covered by snow.