If you've been following our Heavy Metal Mudder project vehicle (Apr. and May '09), then you will recall that last month we unveiled our plans for running a fully hydraulic steering system. Using a double-ended cylinder from PSC Motorsports, we eliminated the traditional steering gearbox, opting for hoses over hardware.
The reasons were simple: It's tough enough to steer our massive tires off road, the system is relatively easy to assembly, and it can be dialed in so the rig can be run safely at speed. "At speed" is our way of saying that this is a non-DOT-approved steering setup. However, much like our beadlock wheels, we feel that if set up properly, it can be an intelligent alternative to a traditional steering configuration.
A variety of full hydraulic...
A variety of full hydraulic steering kits are available in the aftermarket. Before purchasing the first part, talk with one of the steering techs from the place where you will be getting your system. Be sure to put together a list of specifics, such as the vehicle's weight, engine, scrub radius, wheel offset, and intended use. These are just a few of the items that will help you determine what setup is right for your rig.
Hydraulic steering systems generally consist of four vital components: cylinder, orbital hydraulic steering control, fluid reservoir, and pump. Acting as a steering gearbox, an orbital uses power-steering fluid to control a cylinder, or ram as it's commonly called. Connecting directly to your vehicle's steering shaft, most orbitals are referred to by the number of wheel locks (turns of the wheel in either direction) they offer. The fewer the turns lock to lock, the more sensitive the steering. Working in conjunction with a beltdriven mechanical pump, the most common type of hydraulic steering system is known as an open-flow system.
Choosing the right orbital, pump, and cylinder for your application doesn't require an engineering degree, but there are a number of variables to consider. Compiled here are a few of the key ideas and components you will need to address when converting your rig to full hydro. Please view this as a general guide, as differences in orbitals, cylinders, and pumps may be great from rig to rig. Your best bet when setting up a full hydraulic steering system is to always consult whomever you decide to get your parts from. Since we opted on a PSC Motorsports kit, we used PSC's years of experience and expert advice to help dial in the best system for our massive Rockwelled rig.
Just like wheels, steering...
Just like wheels, steering cylinders come in many shapes and sizes. One of the big advantages of running a double-ended ram (shown here) is that they require a lower amount of fluid volume to operate. In addition to a more balanced throw from side to side, a beefy double-ended ram will be a better choice over a single-ended, agricultural-style one with cast ends that are a bit weaker and require more fluid to move.
The orbital controls the steering...
The orbital controls the steering movement by working with the pump to deliver fluid to the ram. Orbitals are often referred to by the number of wheel turns lock to lock they provide. The vast majority of your steering's sensitivity resides here. For example, if you have a rig that you plan on driving fast, a slower orbital (one that requires more turns of the wheel) might be a better fit because it will have less quickness and a less sensitive feel than a faster orbital.
Connecting your original steering...
Connecting your original steering linkage to the orbital is as easy as bolting on a steering adapter to the top of the orbital. Depending on the length and shaft joints, you can mount the orbital almost anywhere. We chose the outside of the frame so we could free up space inside the framerails and keep an eye on all our fittings and hoses.
Pumps are referred to in gallons...
Pumps are referred to in gallons per minute (gpm). It's important to match the gpm to the cylinder because each will need a certain amount to work correctly. Your engine and factory pump size are contributing factors when picking out the correct pump. Generally speaking, an aftermarket pump will bolt in place with little to no modifications. In our case we were still able to retain our factory serpentine belt.
Since fluid is now the key...
Since fluid is now the key element to your steering, you'll need an external reservoir to meet the increased fluid demand. Be sure to mount it above the pump and as far away from any direct heat sources as you can. Also, do not use hydraulic fluid! Regular or synthetic power-steering fluid is all you need.
When routing your hoses, keep...
When routing your hoses, keep them off sharp or jagged surfaces that might cause damage. We like zip-tying our lines together, and it's never a bad idea to carry an extra pre-fitted set with you.
Fluid Thinking
Full hydraulic steering is far from perfect and isn't for everybody. Almost any modification you perform on your rig has a flip side. Whatever you bolt, weld, or drill on can have a side effect. One common mistake many people make when running full hydraulic steering is trying to overcorrect too quickly by forcing the steering wheel aggressively in one direction or the other. If you try to jam the wheel too quickly, it will interrupt the pump flow, which can only fill and empty so fast.
Steering with a fully hydraulic system can feel almost effortless at times, which can make you forget that you're still moving a heavy load. Like we said before, it's not perfect, but it is a simple and really easy solution for those of you with rigs where traditional steering simply isn't an option.