Cooperman thanks for confirming and adding info re the DOT acronym.
Thierry, thanks for your pic of the ABS unit confirming it has an integral pump.
Clemens with the benefit of your pics, it seems that the master cylinder is of the dual circuit type, and operates with servo assistance.
As ever I claim no expertise, I come here in the hope of learning.
I suspect the dual circuit master cylinder will supply braking pressure to two wheels on each circuit.
With the engine running and thus supplying vacuum to the servo, the servo will multiply the pedal applied pressure, which should provide all braking power required and which alters braking performance relative to the variation of pedal pressure applied by the driver.
In a situation of servo failure, increased pedal pressure is required to equal the same braking effect as was the case when the servo was operational.
With the car stationary and a foot applying pressure to the brake pedal, then the engine started, it can often be the case that the pedal will move further under the originally applied pressure, suggesting that an increased amount of pressure has been applied to the brake circuit..?
If any one hydraulic circuit fails, i.e due to fluid leakage, then both wheels on that one circuit will loose pressure, the remaining two wheels on the other circuit will still have braking power applied relative to the pedal pressure applied, however I suspect the pedal travel will increase before pressure build up in the remaining operational circuit is achieved.
I expect if one circuit fails, a brake failure indication will appear on the dash, and the relevant signal sent to the ABS unit`s ECU in order that it operates according to the way it has been configured to operate it`s valves in a circuit fail situation....?
I do not know the lay out of dual circuits configuration on new Morgans, could be diagonally across the car or front and rear fed separately.
This vid seems to provide a reasonable generic explanation of ABS operation for any one wheel.
https://www.youtube.com/watch?v=-IUZWwMm7nYI spent some time wandering the web in an attempt to define the ABS unit`s hydraulic pump motors exact function (if fitted) and failed to do so to my own satisfaction/understanding.
if anyone knows the exact function of the pump, I would be grateful if they could educate me/us.
If you watched the vid via the link above, it suggests the purpose of the pump is to "return" fluid in a pulsing action back up the same line that is supplying pressure to any one circuit of brakes, these being the pulses which can be felt through the brake pedal when the ABS unit is called into action.
I do wonder if any fluid is being "returned" as suggested in the vid..? It seems more likely that the pulsing of the valve is that which is felt at the pedal and it is the pump that generates the pulsing pressure felt while at the same time the valve is being electrically pulsed to restrict pressure to the brake at risk of locking the wheel, the pump relieving the pedal generated pressure at the wheel by working against it, described in the vid as "returning" fluid..???
Given that I suspect any one of the two lines supplying pressure generated by the master cylinder to then merely pass through the inactive ABS unit and on to the two wheels in that one circuit, It would seem that if/when the ABS unit is called into action, that "pumping" fluid back up the line to the master cylinder would affect the brake pressure being applied to both wheels on that one circuit..?
I have found web site suggestions that the ABS pump supplies pressure to the wheel brakes, as opposed to "returning" fluid to the master cylinder as in the vid, or perhaps more likely to be making pulses felt through the pedal to advise that the ABS unit is active..?
As is ever with ECU controlled units they can be programmed to operate in a variety of different ways relative to the variation of inputs at any one moment in time, and trying to apply simple electro/mechanical logic is unlikely to cover all possible operational scenarios.
To add to the complication of gaining full understanding, it seems manufacturers may be unlikely to provide a step by step guide as to the way the ECU`s outputs are designed to operate relative to input signals, tending to quote intellectual copyright protection as a reason for not providing information on the programming/configuration of any ECU`s control strategy...? All of which creates probable misunderstanding when using electro/mechanical logic when attempting to understand the stages of operation of any particular control unit..
With the above in mind it seems possible that a few different interpretations of actual operation of the same unit may be found out in the
www..? Always happy to be corrected if I have got anything wrong.
