Transformer question

I will soon be making a power supply for some servo motors. I have a
large transformer that I pulled from a piece of equipment my company
was getting rid of. It produces about 30 volts and judging from the
size of the wires, I think it can supply at least 15 amps. More than
enough for what I need. Unfortunately, the servos that I want to use
are rated at 24 volts, so before I go looking for another
transformer, I would like to ask the group if there is a way to
limit the voltage of this transformer. It seems to me that I
remember seeing circuits that used a zener diode to reduce voltage.
Am I way off base here, or can this be done?

Thanks,
Tom Murray