They go by many names—post pounder, post knocker, fence driver, and most commonly, post driver. But what are they and how do post drivers work? The post driver is like many other power tools—a device that’s existed in one form or another for centuries but has a contemporary, powered equivalent that relies less on your muscle and more on clever engineering.
What is a Post Driver?
A post driver is exactly what it sounds like. It’s a tool used to drive fence posts into the ground. Planting fence posts may seem like an easy task, after all, they only require a hole in the ground, but it’s a bit more complicated than that. The last thing you want is for your fence to fall over because its posts were installed too shallowly into the ground. Most of all, your posts need to be snuggly rooted into the ground so they stand tall even against the outside elements. What a post driver does is give you uniform downward motion against the post, which ensures it’s driven deeply into the ground with minimal damage to the post. Post drivers come in many iterations:
Manual—This type of post driver relies on the lifting force of a person. Yet, due to its design, it requires much less energy than a hammering tool like a sledgehammer.
Pneumatic—These aren’t very common outside of job sites. They’re powered by an external air compressor.
Gas—A gas post driver is the choice of most people who are looking for a post driver that doesn’t require the brute force of a manual model.
How Do Post Drivers Work?
The fundamental principles behind post drivers, regardless of their engineering, are all the same. They apply broad, downward force onto a post, driving it evenly into the ground. But how do post drivers work?
Manual Post Drivers Are Human-Powered
Manual post drivers are examples of the kind of perfect human engineering we should all be proud of. Their design is simple yet impactful. In essence, with a manual post driver, you lift and drop the “pounder” over top your post. The pounder has an open end that is more-or-less the diameter of a post, which fits within the hollow pounder. The end of the pounder is closed and the post strikes against it. Because the post is fed through a hollow tube without much wiggle room, the striking energy is largely retained, resulting in a hard, consistent hit that relies more on the weight of the pounder and resultant striking force than the strength of the operator.
Pneumatic Post Drivers Use the Power of Air & Pack a Punch
On the other hand, pneumatic post drivers use the power of air. The fundamental principles are the same as its manual cousin, but instead of the operator lifting the pounder, the pounder is elevated through the use of air pressure, after which the operator presses a switch to cut the air supply, driving the full weight of the pounder against the post. Pneumatic drivers, while bulky, can lift a lot of weight with little effort, thus making quick work of what is typically a quite a lot of manual labor. But just like all traditional pneumatic power tools, you’re going to need to have a large air compressor on site, which is bulky and impractical.
Gas Post Drivers Are Extremely Portable and Cleverly Designed
Lastly, gas powered post drivers use the power of a combustion motor to drive your post into the ground. Typically, you have two sizes: 35cc Post Drivers and 50cc Post Drivers. However, gas post drivers vary the most from the rest. The motion of a gas powered post driver is more like an extremely fast tapping. Like that of a jack hammer. Gas post drivers aren’t smashing a weight against a post as much as they are precisely vibrating it into the ground. It’s a clever trick and makes quick work of your post-driving job. Because they only rely on gas, this variety of post driver is as portable as the manual version, yet much more powerful.
Which Post Driver is Right for Your Job?
That’s a tough question to answer and it varies, depending on your needs. In either case, manual and gas-powered post drivers can both be rented from an equipment yard, so you should focus on those two options. A pneumatic driver, while powerful, may not be available in your area and requires an intricate setup.
But be it manual or gas, you’ll want to gauge the size of your job. And depending on the season, where you live, and the amount of work ahead of you, you may want to go straight to a gas powered post driver. Manual post drivers, while a tried and true feat of human ingenuity, will take a lot out of you. Whichever you choose, make sure to take a moment to appreciate the fruits of clever engineering now that you’ve answered how post drivers work!