bellows (fig. 7-14). A bulb located on one end of the capillary tube is filled with fluid and then is put in the heat zone. It transfers heat-created pressure through the capillary to the diaphragm. The expanding diaphragm presses a system of levers that snap the electrical contacts open, thus cutting off electrical current to the controls. Automatic recycling takes place with slight temperature drops, maintaining a constant set temperature. the two small, slotted lock screws (fig. 7-14) that are behind the dial. Now, with one hand, hold the main center hub of the control and move the slotted adjusting plate to the right to raise the temperature or to the left to lower the temperature. That is a delicate adjustment, so move the dial a little at a time.

Certain types of hydraulic controls have a safety device, normally set at 450F, that trips upon reaching the set temperature and requires manual resetting. It may take several hours before the appliance has cooled down enough to allow the operator to reset the unit.

If you find that the circular slots in the adjusting plate prevent you from turning the plate for the desired temperature change, remove the two lock screws carefully so you can move the adjusting plate a full 180 degrees. Replace the two adjusting screws and continue the calibration process as before.

Repairing a hydraulic control is usually limited to adjusting the temperature setting to correspond with the temperature recorded in the appliance. You can adjust the temperature control by loosening, but not removing,

A timer is used to control a circuit to an appliance automatically or give a warning to the operator that a predetermined time has lapsed. Figure 7-15 shows a typical wiring diagram of an electric range single-pole oven timer.

Figure 7-14. - Hydraulic control.