Forklift combination switch unstable performance solution

Combination switch has been in my current company F-Series 2 ~ 4 t forklift widespread use, but there are performance instability. After repeated dismantling, analysis, confirmed the main reason is as follows: turn the handle knob switches the moment, the contact area between the contacts is small, and the current has changed dramatically over time will cause contacts fever; long-term use, touch point produce wear, oxidation and corrosion, increasing the contact resistance between, thereby causing more heat contact.
Contact the handle body heat will cause the contacts loose or adhesion, so that combination switch fever, unstable performance, or even functional failure. Used in combination switch shape and contact position shown in Figure 1, additional gear lever combination switch and wiring shown in Figure 2.
For combination switch performance and stability, longer life, should be reduced by the current contacts, in order to reduce the contact heat. And reduce contact through the current most convenient way is to increase the bypass switch, the current shunt. The study identified specific approach is to add a bypass switch combination auxiliary electrics tacker relays, continued electrical model HD4195A, contact capacity 40 A.
Combination switch improvement before and after the circuit is shown in Figure 3. Modified combination switch works as follows: No. 10 for the switching power supply cord into the line end, line number 11 is showing the wide lights switch output lines, line number 9 for the headlight switch output lines (headlight power is 110 W, power-current of about is 10 A). When the headlight switch is turned on, the combination switch 10,9 contacts contacts of the relay solenoid is energized, then the main relay contacts connected to 10,9 connection. Improved ability to electrify the line switch contacts has been significantly strengthened, even if there are fluctuations in the load current power supply, it will not damage the combination switch contacts, thus avoiding the heat and burn the combination switch contacts phenomenon. Experimental results show that the improved combination switch to achieve the desired effect, the relay performance instability does not occur again