page_title: Pull-rod suspension
section_title: Design
hierarchical_section_title: Pull-rod suspension / Design
caption_attribution_description: English: hydraulic a.d.Tramontana Ride-Height System
context_page_description: Pull-rod suspension and push-rod suspension refer to a specialised type of automotive suspension system which is largely based on a double-wishbone system, incorporating elements of the commonly used MacPherson strut.
  In cars, suspension refers to the system by which the vehicle maintains contact between all of its wheels and the ground. This is commonly achieved via use of dampers and springs, providing downward forces on the wheels to counteract impact shocks. However, this strut is mounted across the chassis, parallel to the ground, as opposed to the perpendicular system commonly used. Push-rod suspension systems therefore allow essential components to be moved out of direct air flow, closer to the centre of gravity, and allow the centre of gravity to be lowered, thereby creating a more efficient distribution of weight and management of body roll.
  As a result, push-rod suspension systems can provide a unique avenue for performance, albeit at the cost of everyday drivability, practicality and comfort.
context_section_description: Push-rod and pull-rod suspension are similar yet distinct in design, with the main difference being the placement of the rocker arm that controls shock damping in relation to the upper control arm. In effect, this means that both push-rod and pull-rod systems are functionally the same design.
  In a push-rod suspension system, there is an upper and lower control arm, similar in design to a double-wishbone frame, which provide a structurally integral connection between the wheel hubs and the chassis. These arms are able to pivot inwards towards the centre of the vehicle, meaning that as the wheels experience shocks from the ground, they move up and down.
  Between these two wishbone control arms, the wheel hubs connect to a rigid ‘push rod’. Here, as the wheels move latitudinally, this rod will push upwards against an oscillating rocker arm, creating a ‘see-sawing’ motion that transfers latitudinal forces from the ground into longitudinal forces inwards towards the chassis.
  On the opposite end of this rocker arm is a transversely mounted shock-damping coil-over, similar in design to those MacPherson struts commonly found in production cars. Therefore, as the wheels move up and down in relation to the road, forces are transferred inwards towards the solid monocoque chassis, as opposed to upwards into the vehicle. As such, push-rod suspension systems allow for much greater high-speed stability, much lower levels of body-roll, and a much lower centre of gravity for the vehicle.
  For pull-rod suspension systems, the only difference is the orientation of the rocker arms. In a push-rod system, the rocker arms are placed at the highest point in the assembly. As such, the rod is under pressure as it transfers compression forces upwards into the rocker arms. In a pull-rod system however, the rocker arms are located between the upper and lower control arms, at the centre of the assembly. As such, the rod is under tension as it pulls against the rocker arms.
  Additionally, the steering mechanism in push-rod suspension systems is much different from conventional vehicles. In a conventional steering system, the steering wheel connects to a steering column, a form of ‘rack and pinion’ gear that translates rotational motion into linear motion, which turns the front wheels. In a push-rod suspension system, however, the steering is controlled by ball joints found at the ends of the control arms, which allow for the wheel hubs, and the car to turn.
  As a result of these factors, the push-rod layout is distinct from other suspension systems as, unlike others, it is able to be designed and assembled with components closer to, or further from, the centre of gravity of the vehicle. As a result, engineers are able to optimise the performance of their vehicle in this area as they sacrifice comfort and practicality in favour of aerodynamics, handling, and stability on track.
caption: Shock-damping system
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