Brake System Design and Optimization: Master Cylinders
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Master Cylinders
03.46
| 00:00 | - Earlier in the course, we learned that making use of hydraulics is a core part of any braking system. |
| 00:07 | The master cylinder is really the first part of the hydraulic system that we need to cover as it's responsible for providing the hydraulic pressure that actuates the rest of the brake system. |
| 00:18 | Looking at a cut away view of a simple master cylinder, we have the main cylinder with the piston. |
| 00:24 | The piston is what's acted on, either with the rod connected to the brake pedal or in OE applications by the rod actuated by the brake booster. |
| 00:35 | At the top of the cylinder is a reservoir or reservoir connection. |
| 00:40 | This ensures that there's always sufficient brake fluid available to the master cylinder. |
| 00:46 | At the end of the master cylinder, there's an outlet which is where the pressurised fluid exits. |
| 00:52 | As the piston is forced down the bore, the raises the pressure inside the fluid as it squeaks. |
| 00:58 | We know from earlier in the course that the amount of hydraulic pressure we build is a function of the force applied to the back of the piston and the piston diameter. |
| 01:08 | There are two main types of master cylinders, tandem and dual. |
| 01:13 | Tandem is what you'll find in most OE applications. |
| 01:17 | While not initially obvious from the outside, tandem master cylinders have two separate cylinders within a single body, stacked end to end. |
| 01:27 | There are a few different reasons for this. |
| 01:29 | The first is that we generally need to have different piston diameters for the front and rear brake circuits as each circuit will have different pressure requirements. |
| 01:38 | The second is redundancy. |
| 01:41 | Having two cylinders means that even if one circuit develops a leak, there will still be some braking force available on the other. |
| 01:49 | Another reason is cost, stacking the master cylinders end on end like this saves money by only needing to maufacture a single cylinder body. |
| 01:59 | As well as simplifying the pedal box and booster mechanism. |
| 02:03 | The last reason is packaging. |
| 02:06 | It simply takes up less space in the engine bay. |
| 02:08 | A dual master cylinder setup is what you'll see in most motorsport applications. |
| 02:14 | This is where two totally separate master cylinders are fitted usually side by side. |
| 02:20 | The main reason for shifting to this style of setup is to allow the use of a brake bias bar. |
| 02:26 | As we discussed in the previous module. |
| 02:29 | This gives us the ability to tune the brake bias. |
| 02:32 | There are many different configurations available for master cylinders. |
| 02:36 | In particular for a dual setup, they're available with integrated or remote reservoirs, different bore sizes as well as single or multiple outputs which gives the user the option to connect a brake pressure sensor directly to the master cylinder without adding extra plumbing. |
| 02:54 | In any case, the key factor we're concerned with is bore size as remembering back to the brake systems hydraulic module, this is what determines the hydraulic pressure that's generated. |
| 03:05 | More specifically, a smaller master cylinder would generate a higher pressure for a given pedal input and vice versa. |
| 03:13 | But a smaller master cylinder will also need to move through a longer stroke to displace the same amount of fluid. |
| 03:21 | In summary, the brake master cylinder is the component in our braking system responsible for building hydraulic pressure. |
| 03:28 | Master cylinders are available in a wide range of styles and configurations. |
| 03:33 | The diameter of the piston or bore size is the more important parameter to take note of as it determines how much pressure we build for a given input force. |
