This idea is going to appeal to the gear-heads, the automotive groups and the big kid that hides in all of us.
Have a word with a contractor or heavy equipment rental facility in your area, and arrange for some large equipment — such as earth movers, excavators and bulldozers — to be made available. You might be able to get a fire truck, ambulance or hook and ladder out of the local fire department too.
You can charge admission to the event to raise funds for your group, though make sure you have a concession stand so the kids can enjoy themselves to (you could rent out model train rides for the youngsters for example). A bucket ride in the hook and ladder fire truck is also sure to be a family favorite, while many attendees will enjoy the novelty of an ambulance ride that doesn't end up at the local emergency room.
You might want to add classic cars to the mix (another idea that will appeal to the whole family) as well as a do-it-yourself clinic where qualified operators can demonstrate to the grown ups how the machinery actually functions.
Another idea is to put together some races or challenges (for a fee) — moving a dirt pile from one location to another, for example. Charge a nominal fee and have midway style prizes available for the winners. As for the little ones, make sure you have branded hardhats available for them (or their parents) to buy.
For full details on holding a tractor pull fundraiser you can check out our full article on the topic.