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MOT changes

The DVSA have issued revisions effective 1/2/2019 to their procedure for MOT testing. One which affects Routemasters is a change to the procedure for checking the service brake operation and the low pressure warning system: Inspections 71 and 34. The requirement to test for recorded effort on the brake rollers once the flag has fallen and the engine is stopped has now become more onerous. Instead of noticeable effort required for two brake applications at each wheel, four applications are now necessary.

This is actually a good move since it will reveal incorrectly adjusted microswitches or low accumulator air pressure.

Re: DVSA MOT PSV changes now current

Continuing from the previous important post submitted recently by Mr R Lane dated 21 February 2019.



I would suggest it be of benefit for all Routemaster vehicle owners MOT exempt or not to obtain a copy of the current
up to-date version of the GOV.UK MOT Inspection Manual regarding Section 1 Brakes.

I quote in part,

Section 1.1.12 Flexible Brake Hoses refers:-

Sub-sections (a) to (f) all now become item failures (PG9)
Sub-Section (b) had it's category upgraded from minor to major with effect from 13/09/2018.

Section 1.1.15 Brake cables, rods, levers, linkages inc brackets refers:-

Sub-sections (a) to (f) all now become item failures (PG9)

Note:- The PSV Inspection Manual Instruction No59 of Procedure & Standards states in respect of Sec 1.1.15:- A rod or lever reduced by wear of more than 1/3rd of its original diameter is classed a failure.

By the authors interpretation this wear also applies to the base brackets sliding adjustment aperture, of which the operating link arm is attached to, thus operating the brake adjuster.


Section 1.1.18 Brake slack adjusters refers:-

Sub-sections (a) to (c) all now become item failures (PG9)

Note:-In sub section (a) above, the radial movement (measurement) of the arm was always thought to be 25mm of a radius length of 150mm.

This is not now the case. The correct radial movement (measurement) is now reduced to 9.5mm maximum, at a radius length of 150mm.

My bus number (if any): Ex LTE Bus Engineering. AMIRTE. CPC-HGV

Re: DVSA MOT PSV changes now current

Michael J Langley
Continuing from the previous important post submitted recently by Mr R Lane dated 21 February 2019.



I would suggest it be of benefit for all Routemaster vehicle owners MOT exempt or not to obtain a copy of the current
up to-date version of the GOV.UK MOT Inspection Manual regarding Section 1 Brakes.

I quote in part,

Section 1.1.12 Flexible Brake Hoses refers:-

Sub-sections (a) to (f) all now become item failures (PG9)
Sub-Section (b) had it\'s category upgraded from minor to major with effect from 13/09/2018.

Section 1.1.15 Brake cables, rods, levers, linkages inc brackets refers:-

Sub-sections (a) to (f) all now become item failures (PG9)

Note:- The PSV Inspection Manual Instruction No59 of Procedure & Standards states in respect of Sec 1.1.15:- A rod or lever reduced by wear of more than 1/3rd of its original diameter is classed a failure.

By the authors interpretation this wear also applies to the base brackets sliding adjustment aperture, of which the operating link arm is attached to, thus operating the brake adjuster.


Section 1.1.18 Brake slack adjusters refers:-

Sub-sections (a) to (c) all now become item failures (PG9)

Note:-In sub section (a) above, the radial movement (measurement) of the arm was always thought to be 25mm of a radius length of 150mm.

This is not now the case. The correct radial movement (measurement) is now reduced to 9.5mm maximum, at a radius length of 150mm.
Note:-In sub section (a) above, the radial movement (measurement) of the arm was always thought to be 25mm of a radius length of 150mm.

This is not now the case. The correct radial movement (measurement) is now reduced to 9.5mm maximum, at a radius length of 150mm.

I wasn't aware that it had ever been 25mm, that is a lot. I checked the oldest version of the manual (1987) I have and that says 9.5mm.

However there has been a significant mumber of changes to standards recently particularly with the revision in May last year. For a while they had considerably tightened up the smoke limit for pre July 2008 vehicles using a figure on the manufacturer's plate, but this now appears to have reverted to normal.

Re: DVSA MOT PSV changes now current

Does the wording define "noticeable effort"?

I usually check by the number of applications before the flag drops, but as roy has said, the 4 apps test may show up incorrect microswitch settings. I've done the "how many apps" test in the workshop with test gauges on and there's been about 20 apps with "noticeable pressure" until it dropped to zero.

Didn't part of the test used to require no noticable drop in pressure in a period of 20 minutes or something similar?

My bus number (if any): RML2532

Re: DVSA MOT PSV changes now current

Mr Roy Gould,

Reference to your 3rd paragraph this will now read under No 38 Service Brake Operation PSV Inspection:-


"Full pressure hydraulic system pressure is not maintained for 10 minutes when the brakes are off and the engine stopped."

Deficiency Category is Major = Failure

My bus number (if any): Ex LTE Bus Engineering. AMIRTE. CPC-HGV