Throughout the history of automotive development hydraulics have played a critical role in the engineering of brakes, steering and gears, as well as suspension. Specialist functions on road going vehicles as well as vehicles designed for non-road use, such as tractors, other agricultural machinery and military vehicles, also use hydraulic power to effect movement of harvesting machinery, aerial ladders and artillery. Hydraulic engineering offers a tested and trusted way of effecting actions with a quick response time and most importantly, it is reliable, efficient, and easier to fix than electrical systems designed to do the same.
Electrical systems are becoming more commonplace in road going vehicles, as the move to all electric or hybrid powered cars starts to take off in the mainstream. Electric actuators are starting to replace their hydraulic equivalent in some systems, especially those from manufacturers who are pro-actively making advances in alternative car design; self-driving cars and fully electric vehicles are pushing electric actuators to the fore of the minds of automotive designers. The appeal to designers is the easy integration of electrical components into an existing electrical system; if most of the controls are electric rather than mechanical it makes sense to extend the same technology as far as possible. Electric actuators are cheaper, easier to control and generally last as well as hydraulic actuators, and it is far easier to work these into the wiring and software system of a vehicle than to install a separate hydraulic system just to run the brakes, or the gearbox.
Advanced braking systems are one of the more important uses of hydraulics in motor vehicles. Hydraulically operated brakes are much more responsive and deploy very quickly compared to electric brakes. Although there is an argument for electric motors being used to achieve regenerative braking in electric and hybrid vehicles, these systems still use hydraulics for the quick action that is required when the brake pedal is pressed. ABS systems also rely heavily on the speed with which hydraulic brakes act; a miniature hydraulic power pack controls the system to deploy the brakes up to sixteen times per second in a skid situation, a speed which cannot be achieved by electric actuators. Mechanical brakes have a strong future in motor vehicles for safety reasons, and this will remain the case until electric actuators can replicate the speed at which a hydraulic system can function.
Gearboxes have been hydraulically operated since the early 1940s, when General Motors introduced the technology to its range. Although they were first developed in the 1920s, it took a while for the new design to be accepted and fitted in the new cars they were producing, but very little has changed since, apart from the introduction of solenoid valves in the early 2000s. Electric systems are now integrated into the control of the gearbox, especially for the twin clutch, but the mechanics at the centre of gearbox function are still hydraulic. This is one of the areas in which electrics will really have to try hard to oust hydraulics, and the only way hydraulics will be replaced here, may be if an engine can be developed where a gearbox is no longer needed.
Motor vehicles have used hydraulic dampers in suspension systems since the humble leaf spring fell out of favour. Even though some modern suspension systems (which allow the driver to adjust the settings for a particular driving style or road type) use electrics to adjust the shock settings, it is still hydraulics that effects the suspension action. Even electric vehicles use hydraulic suspension, as it is the best solution, and despite some manufacturers looking to recover energy from bumps in the road through an electrical suspension system, the complexity of such a system is not worth the small amount of energy that may be recovered, and certainly not at the cost of replacing a very capable suspension solution with something more expensive and difficult to fix.
Power steering used to be a hydraulic aid to assist drivers in steering and parking; right up to the 1990s there were still cars on the road that did not have power steering and anyone who has ever driven one, will attest to the huge difference that power steering makes to the driver. The first power steering systems used hydraulic pumps to provide the driver with extra power, but these have long since been replaced with electric motors. Self-parking cars are already widely available and these would not be possible without electrically operated steering. Power assisted steering is one area where hydraulics has already fallen out of favour and electrics have taken over.
Hydraproducts’ miniature and micro hydraulic power packs are ideal for the automotive industry, and are perfectly suited to use in suspension, braking and power steering systems. Although there are some areas of automotive engineering where electrics have taken over, the key areas mentioned above are safe for now. Other areas have seen a better integration of electric and hydraulic systems, with the benefits of each being user harmoniously to affect the best system possible. As new designers emerge into the automotive market and look to shake things up, we may see electrics replacing hydraulics at least in the design and testing stage, but the reliability and relative simplicity of hydraulics means it will always have a place in the automotive industry.