How should I understand this twin coil relay pinout? (Screenshot)
This relay has two coils:


First coil is between pins 1 and 2. It triggers the double throw switch with the common 6, NO 8 and NC 5.
The second coil is between pins 3 and 4. It triggers the double throw switch with the common 7, NO 8 and NC 5.


It appears that pin 8 and 5 should connect to the battery (+) and (-). Power coil 1-2 and the motor gets (+) on 6 and (-) on 7. Power coil 3-4 and the motor gets (-) on 6 and (+) on 7.

If both coils are powered, the motor is off and shortcircuited (it gets connected with its both poles to the (+)).