In recent RET-Monitor features we have considered several aspects of transmission design and engineering, each time with the implicit assumption that some means of gearing between the power unit and road wheels was a prerequisite feature.
Why should this be so, and how do we then determine what we need?
Essentially we seek to transform rotational motion Read more…
One of the problems faced by race car designers is the conflicting requirement of keeping a low centre of gravity for the engine (and transmission), whilst keeping the driveshaft within acceptable values. Whatever the chosen method of coupling excessive angularity will lead to increased power losses and ultimately, failure of the joints.
Putting some numbers to this, consider a Formula Three car whose engine is dry sumped and running a 140 mm diameter race clutch on a lightweight flywheel. Read more…
The appearance of the pull type clutch in the race car world in the last decade was driven mainly by considerations of efficiency, consistency, and component life. These factors are improved by an increase in the mechanical advantage of the release mechanism.
Starting with the basic operation of a conventional ‘push’ clutch, the ‘push’ that is delivered by a slave cylinder refers to the force that is required to disengage the clutch plates. Upon depressing the clutch pedal, hydraulic fluid is forced into the cylinder which is then thrust out Read more…
The traditional race car multi plate clutch is essentially a friction drive that transmits engine torque into the transmission itself. Layers of plates are alternately geared to the clutch housing, which is bolted to the engine flywheel and also to the clutch hub, which is splined to the gearbox input shaft. When a heavy axial, or clamp load is applied to the assembly, the friction produced between plates prevents any rotation between them and we have a solid drive without any additional mechanical engagement. Transmitting this drive depends on maintaining the clamp load. This is usually obtained by Read more…
In previous Monitor features we have touched upon the automated gearshift of a modern race car and attempted to put it into historical context, but how many of its mechanical design features represent new thinking ?
Central to its function has been the move from a H-gate to sequential gear selection, for with this it is much easier to provide powered control of the actual selection mechanism. In the modern box this normally takes the form of a drum, with a pathway machined into it, whose axis is parallel to that of the actual gear shafts. Read more…
Up until the end of the 1950s, when the front engined Grand Prix car predominated, it was not uncommon to find it’s transmission attached to the engine bell housing, in classic road car configuration, with the box itself almost always in-line, and often road car derived. But it was equally the norm to find the transmission in unit with the rear axle and differential, particularly in a thoroughbred racing design, in which case it was as common for it to be aligned transversally, as in-line.
When the mid-engined car began to take over Read more…
The conventional H-gate manual shift gearbox, a universal feature on all race cars until about 20 years ago, is actually a highly counter intuitive control device…
Consider the conventional passenger or race car control system:
First, we have the right hand ‘throttle’ pedal – if you press with your foot you go faster, release your foot and you slow down – logical enough. The second pedal, well, if you want to slow down a lot faster, or in an emergency Read more…
It can be sobering to sit back and consider what we ask of a racing car gearbox when we require it to perform a structural role as well as functioning as a change speed box…
Generally the loads that we will ask it to absorb are a significant proportion of, or even a multiple of all up vehicle weight, and they will act in a variety of directions and combinations.
Until relatively recently it has been acceptable to keep racing gearboxes relatively simple and add ancillary systems externally. But space inside a racecar is at an ever-greater premium, mainly due to the overriding demands of aerodynamics squeezing the internal volume in pursuit of better airflow. It was once perfectly acceptable for oil pumps and filters to be mounted in the lines to the gearbox oil cooler. But now these things are an unwelcome accessory and racecar designers want to see them integrated into the ‘box.
Back Torque Limiters - what are they and why would you possibly need one?
More commonly known as slipper clutches the back torque limiter has been one of the major growth businesses in motorcycling during the last few years.
Its all about grip and smoothness. Motorcycles have tiny tyre contact patches compared to cars and the racers that can manage that contact patch and maximise the grip available will be the winners.. Read more…
