Handbrake - clever design feature
01 Nov 2012 11:14 #1
by dandjcr
David and Janet Ribbans - Oka 148
Oka148 profile here.
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dandjcr created the topic: Handbrake - clever design feature
Forum Home > OKA Maintenance > Handbrake - clever design feature.
Tony Lee
Member
Posts: 539
I guess those with over-developed left shoulders and upper arms have to be careful they don't pull so hard on the handbrake handle that they break the cable.
They may not realise they have access to a force limiting feature that is easily implemented by slipping the cable off the nylon pulley. This extra friction cleverly reduces the strain on the cable and the brake mechanism.
Of course those no so well endowed need to make sure that the previous owner didn't make use of the feature and check that the cable is indeed running between the lips of the pulley instead of just beside it - and the only way this can be done is by feel.
I didn't realise that 123 had the force limiting feature engaged and being a 90kG weakling, I had been concerned for a long time about the emegency brake with no emergency stopping capability. In fact even on a flat bit of concrete, any decent wind from in front of behind was enough to overcome the paltry holding power.
Little bit if fiddling to get the cable back where it belongs and now my fingers are crossed that I will have a handbrake at last.
Certainly worth checking.
--
Tony
picasaweb.google.com/114611728110254134379
December 13, 2010 at 3:41 PM Flag Quote & Reply
Dandj
Member
Posts: 367
Tony, apart from the cable falling off the pulley, I also had to modify some of parts in the park brake housing.
The cam lever (item 26) fouled a casting lump on the transfer box so I ground out a section to avoid it.
Also the turnbuckle adjuster rod (item 36) was badly worn and of course it was the left hand threaded end which was worn. I found a replacement from a 10 mm fencing wire turnbuckle, which uses a LH threaded rod. I chopped off a section and welded that on. Ensure the internal threads in the clevis blocks are OK, you don't want the threads to fail on a steep slope.
The cable can probably only fall off the pulley if it's too loose (ensure the return spring (item 41) is working or fit a stronger one) or if the pulley pin is stuffed.
With these mods the park brake is quite effective at holding a 6 tone Oka on a slope, but I do still worry that there's not actually very much holding it and a solid lever brake would be preferable.
There was some discussion on alternative park brake solutions here. Lengthening the operating lever (item 2) seems a good idea. Peter Furlong also replaced the handle/pulley arrangement in the cab with a lever mechanism, see here. Both will increase the pulling force but it still relies on the cable and turnbuckle items for reliability.
--
David and Janet Ribbans, Oka 148
December 15, 2010 at 9:29 AM Flag Quote & Reply
Dandj
Member
Posts: 367
Sorry about the multiple photos, shouldn't use 2 different browsers at once, they (and I) get confused, and 10 min to edit is not enough (Hal, can you extend this to 15 or 20 mins?).
--
David and Janet Ribbans, Oka 148
December 15, 2010 at 9:44 AM Flag Quote & Reply
Hal Harvey
Site Owner
Posts: 510
I don't think I can extend the time David, working with somebody else's creation here so there are always things I can't do... but I did fix the photo... actually I just made you an Administrator, so if that achieves what I think it does, you can now go back and edit anybody (not just yourself) at any time. Who needs a V8 when you have power like that.
--
Hal
December 16, 2010 at 12:43 AM Flag Quote & Reply
Dandj
Member
Posts: 367
Thanks Hal,
I shall use the power wisely.
--
David and Janet Ribbans, Oka 148
December 16, 2010 at 10:36 AM Flag Quote & Reply
John & Laura Szkoruda
Member
Posts: 111
Use your power wisely. ----** May the force be with you both. !!! Ha ha Sounds like Star Wars. Hope you all have a merry xmas & a great & safe New Year.
Regards to all Especially you Hal for all the work you have put into the web site, and all that have contributed to make interesting reading. And Hal & Joe for your very kind offer of help when our son was injured.
Best wishes John & Laura
--
John & Laura Szkoruda OKA 147
December 18, 2010 at 8:00 AM
Tony Lee
Member
Posts: 539
I guess those with over-developed left shoulders and upper arms have to be careful they don't pull so hard on the handbrake handle that they break the cable.
They may not realise they have access to a force limiting feature that is easily implemented by slipping the cable off the nylon pulley. This extra friction cleverly reduces the strain on the cable and the brake mechanism.
Of course those no so well endowed need to make sure that the previous owner didn't make use of the feature and check that the cable is indeed running between the lips of the pulley instead of just beside it - and the only way this can be done is by feel.
I didn't realise that 123 had the force limiting feature engaged and being a 90kG weakling, I had been concerned for a long time about the emegency brake with no emergency stopping capability. In fact even on a flat bit of concrete, any decent wind from in front of behind was enough to overcome the paltry holding power.
Little bit if fiddling to get the cable back where it belongs and now my fingers are crossed that I will have a handbrake at last.
Certainly worth checking.
--
Tony
picasaweb.google.com/114611728110254134379
December 13, 2010 at 3:41 PM Flag Quote & Reply
Dandj
Member
Posts: 367
Tony, apart from the cable falling off the pulley, I also had to modify some of parts in the park brake housing.
The cam lever (item 26) fouled a casting lump on the transfer box so I ground out a section to avoid it.
Also the turnbuckle adjuster rod (item 36) was badly worn and of course it was the left hand threaded end which was worn. I found a replacement from a 10 mm fencing wire turnbuckle, which uses a LH threaded rod. I chopped off a section and welded that on. Ensure the internal threads in the clevis blocks are OK, you don't want the threads to fail on a steep slope.
The cable can probably only fall off the pulley if it's too loose (ensure the return spring (item 41) is working or fit a stronger one) or if the pulley pin is stuffed.
With these mods the park brake is quite effective at holding a 6 tone Oka on a slope, but I do still worry that there's not actually very much holding it and a solid lever brake would be preferable.
There was some discussion on alternative park brake solutions here. Lengthening the operating lever (item 2) seems a good idea. Peter Furlong also replaced the handle/pulley arrangement in the cab with a lever mechanism, see here. Both will increase the pulling force but it still relies on the cable and turnbuckle items for reliability.
--
David and Janet Ribbans, Oka 148
December 15, 2010 at 9:29 AM Flag Quote & Reply
Dandj
Member
Posts: 367
Sorry about the multiple photos, shouldn't use 2 different browsers at once, they (and I) get confused, and 10 min to edit is not enough (Hal, can you extend this to 15 or 20 mins?).
--
David and Janet Ribbans, Oka 148
December 15, 2010 at 9:44 AM Flag Quote & Reply
Hal Harvey
Site Owner
Posts: 510
I don't think I can extend the time David, working with somebody else's creation here so there are always things I can't do... but I did fix the photo... actually I just made you an Administrator, so if that achieves what I think it does, you can now go back and edit anybody (not just yourself) at any time. Who needs a V8 when you have power like that.
--
Hal
December 16, 2010 at 12:43 AM Flag Quote & Reply
Dandj
Member
Posts: 367
Thanks Hal,
I shall use the power wisely.
--
David and Janet Ribbans, Oka 148
December 16, 2010 at 10:36 AM Flag Quote & Reply
John & Laura Szkoruda
Member
Posts: 111
Use your power wisely. ----** May the force be with you both. !!! Ha ha Sounds like Star Wars. Hope you all have a merry xmas & a great & safe New Year.
Regards to all Especially you Hal for all the work you have put into the web site, and all that have contributed to make interesting reading. And Hal & Joe for your very kind offer of help when our son was injured.
Best wishes John & Laura
--
John & Laura Szkoruda OKA 147
December 18, 2010 at 8:00 AM
David and Janet Ribbans - Oka 148
Oka148 profile here.
Visit our technical and travel blogs: here.
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