Joined: Aug 2017 Posts: 39 Threads: 15
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Hello,
I readd that the full girling plunger units (the ones with the levers on) should be allowed to 'float' by having the nuts not done up too tight. Does this also apply on the semi girling setup as well. From what I can read this allows some self centering...
David
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No, because the levers would pull one way. Holes not oval or oversize.
Joined: Aug 2017 Posts: 39 Threads: 15
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Hi,
But would this work if you made the adjuster unit 'float" instead as yes of course the pull or semi girling is always in one direction?
Also has anyone tried to put to make these twin leading show by putting expander units at the top and bottom? I saw that this was done from an earlier post on the earlier brakes (Power to Arrest article) but haven;t seen anything similar on girling.......
David
Joined: Aug 2017 Posts: 2,748 Threads: 31
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Location: Auckland, NZ
With the Seven systems there is little scope for self servo effect because when one shoe self activates the cam rotation is restricted by the other so the cam cannot fully follow up and reinforce the full self action. Some other makes had two leading shoe mechanical brakes but the linkage was complex.
With a floating adjuster the whole retardation would then be resisted by the cam; a bit much for as already often bent. And probably problems with grabbing.
I gather some have modified the adj end of shoes so these are free to slide instead of being contained by the the anchor pin or round ended adjuster pistons. Moderns are like this and curiously do not drag, but the normal operation is by piston and straright line. With low power Sevens anything likley to drag has to be avoided.
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22-01-2021, 10:10 PM
(This post was last modified: 22-01-2021, 11:57 PM by wild_willy.
Edit Reason: wrong info in original post
)
I was always under the impression that the semi girling plunger unit was designed to float slightly to allow the shoes to self-centralise in the drum. The fact that the fastener used was a castellated nut and split pin combined with the copper flat washers I thought supported that theory.Not sure it would assist with a self-servo effect though.
Having checked a backplate and plunger I find that there is no room for movement between the backing plate and the plunger unit so my original impression is incorrect.
Joined: Aug 2017 Posts: 522 Threads: 17
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Location: Hampshire UK
The Austin Semi-Girling components which I have seen have been mounted in round backplate holes which are sized to not allow any float.
Curiously, they still use the same castellated fixing nuts and Thackray washers as per applications where float is intended. I have always assumed that this was just production expediency on the part of the suppliers. I believe they were New Hudson Ltd of Birmingham.
