The steering gear in any vehicle is the mechanism which transfers the turning motion of the steering wheel to actuate the front steering axle wheels left and right. Mechanical steering gears can require significant physical effort to turn, especially at slower speeds or when maneuvering in parking or backing situations. Power steering gears, which are most widely prevalent today introduce hydraulic actuation assistance to the gear box, which makes steering your truck far easier. However, as is the case with many systems on your truck, there are some things you should know to keep this important component functioning properly.
In this article, we will describe the function of a power steering system and five tips you may not know about
- Manual Steering Gears vs. Power Steering Gears
- 5 Power Steering Tips You Need to Know Immediately
- Wheelco Recommendation
Manual Steering Gears vs. Power Steering Gears
Mechanical Steering Gears
A manual steering gear is an assembly of gears contained within a housing, and most often referred to as a steering box. Mechanical steering gears are mechanically operated by gears, leverages, and arm strength without any assisted power. However, these steering gears do have lubricant within the housing. There are two basic types of manual steering gears used in heavy duty trucks:
- Worm and Sector Shaft Type
- Recirculating Ball and Worm Type
In the basic worm and sector shaft type manual gear, the main worm gear which is connected to the steering wheel shaft, meshes with the sector gear directly to turn the output pitman arm. This is a fundamental manual steering gear.
The recirculating ball and worm type has a ball nut with internal spiral grooves containing recirculating ball bearings mounted on the worm gear. The ball bearings transmit the turning force from the worm gear to the ball nut, causing the ball nut to move up and down the worm gear. The ball nut also has exterior gear teeth that mesh with the sector gear. As the ball nut moves up or down on the worm gear, it causes the sector gear to rotate, which, in turn, causes the Pitman arm to rotate back and forth. This version of a manual gear represents a progression of the basic manual worm and sector design.
Power Steering Gears
Far and away, the most widely used design in trucks on the roads these days is the Power Steering Gear, sometimes referred to as power-assist steering gears. Power steering gears are similar to a manual recirculating ball steering gear with the addition of a hydraulic assist control mechanism. It is important to note that a power steering system must default to manual operation in the event of power-assist circuit failure. In this scenario, the gearbox is charged with hydraulic fluid under pressure and uses a rotary control valve to control the flow of fluid. The movement of the ball nut is assisted by hydraulic pressure. The very common integral-type power steering has the rotary control valve and a power piston integrated within the gearbox. The rotary valve directs the oil pressure to the left or right chamber to steer the vehicle and a spool valve is actuated by a lever or a small torsion bar located in the worm gear. This whole hydraulic operation is charged via a hydraulic pump driven by belts or direct gear off the engine.
5 Power Steering Tips You Need to Know Immediately
Significant Power steering issues typically do not happen suddenly, but rather tend to be a matter of wear and slow degrade over time. As such, the driver or owner who operates the truck may not realize some of the signals such as excessive steering wheel play and oversteering, tendency to wander in the lane, lack of power assist, and even leakage on the gear itself. Issues with leaks or excessive lash in the output to the drag link are very common DOT violations which are tagged each year. Do not let yourself fall behind. Stay ahead of power steering issues with these 5 tips.
Keep Power Steering Fluid Clean & Full
Power steering fluid is often no concern to you until your power steering pump begins to make noise. These noises are usually a sign that power steering fluid is low. The next question would be “Where did the fluid go?”, followed by “Is there a leak?” Also, if the pump is belt driven, it could be a belt issue. In addition, old power steering fluid that has been degraded by oxidation can loose the ability to prevent wear and tolerate heat as it should. By following your owner’s manual for routine changing of your power steering fluid, you can make sure it stays clean and full.
Proactively Inspect Your Rig
By proactively inspecting your rig on a normal routine basis and paying attention to the signs mentioned below, you can save yourself precious dollars from DOT fines and downtime from being red tagged.
As you are learning, you probably now realize that there is a lot going on in the power steering system in general. Much more so than the old manual gears. Besides just making the truck driving experience much easier for the driver, your power steering gear helps to maintain steering stability and good control. If you consider the mass and speed of your truck going down the road, it isn’t difficult to understand how critical the system is and the possible frightening outcome of what loss of vehicle control could mean. At best, it impacts drivability – At worst, there could be tragedy.
Signs of Power Steering Failure
There are a few easy telltale signs that your power steering gear may be having issues. The easiest of these signs are unknown noises. If you are hearing unfamiliar whines and noises when you are turning the steering wheel, you should immediately check the power steering fluid to see that the fluid is not low or empty. These whines and noises are commonly caused by low or no power steering fluid. In this situation you must also ask where the fluid went and pursue any leaks. Depending upon the nature of the noise, you must also consider drive belts on belt driven hydraulic pumps.
Another possible sign of power steering system failure is decreased steering response time. If you experience your truck’s steering response has changed and that you are having to “oversteer”, that is a sign that your power steering system needs to be inspected and the issue diagnosed. Although the problem could be caused by more than one component in that system, the power steering gear is certainly one of them.
The last sign of your power steering gear having issues is knowing the “drivability” of your rig. Drivers are obviously the most familiar with their own truck and should be able to tell if something is “off.” If you notice any sudden changes in the resistance, feel any surges or undue stiffness in turning, these can be signs of power steering gear internal problems which could require adjustment or steering gear replacement.
Big Job Even for Professionals
Are you thinking of replacing your power steering gear by yourself? If so, you might want to reconsider. Let us tell you why.
Besides just the basic removal and re-installation of the steering gear box, the installer also needs to make sure the hydraulic assist system is bled free of any trapped air. Also, in most power steering gears, it necessary to correctly set the poppets. This is done to set the stops properly for even, full range, left and right. In addition, the pitman arm must be clocked correctly to the steering gear output shaft.
It is also very important to do a thorough inspection of the system wear points beyond the steering gear itself. Steering shaft U-joints, drag link, and even front axle king pin wear all contribute to excessive wear. Even though the steering gear replacement may have been diagnosed correctly, it is very possible that these other points are contributing overall excessive wear and free play. Many manufacturers also recommend front end alignment when repairs to the steering system are done.
Identify & Choose Quality Parts
If you do decide to repair your power steering yourself, it is important to consider the quality aspect in this purchase. Simply getting the correct part or using only price to make your decision may not be the best course of action with this product. Heavy duty power steering gears have very specific engineering specs to operate as designed. So, when you’re choosing a remanufactured power steering gear product, it is important to choose a product which adheres to original specifications and has a thorough and solid remanufacturing process. With the understanding of what the installation job costs, no one wants to do this any more often than absolutely necessary. Product life is very important.
At Wheelco, we only choose to stock quality parts that meet the high pressure demands of the heavy duty industry. Power Steering Specialists continues to prove their power steering gears can stand up to those demands. That is why we recommend Power Steering Specialists for all your power steering gear needs. With a thorough and proven remanufacturing process, they make sure every unit is tested and inspected to ensure their steering gears meet or exceed original equipment specifications.
Visit with our Wheelco team of aftermarket experts and service techs to find the power steering gear that matches your application needs. Give us a call, text, or message us through chat to get started, or stop in to one of our stores today.