Thanks for the reply MrAl
It is no big deal, that it has that lower gain, and all I want is to use the component as a switch with e.g. PWM. The component is not from a catalog, but from an old robotics controller, but the part number is written clearly on the side of it, so I'm sure about that. Actually this small test was designed to test whether or not the component works as it should. I apply a base signal of 7 V and 4 mA to 25 mA, which provides a voltage drop across the load (resistor or motor).
The problem is though, that the power supply to the load does not seam to be used. A higher base current also does not change the voltage drop across the load, which is stead at 4.4-4.5 V no matter all other power supply voltages (of course the voltage is decreasing, when the base power supply is below 4.4 V. So maybe the component is broken