ZF gearboxes
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Anyone noticed that some ZFs lock-up on the first gear, as well as the second gear in some models(all lances)? And also anyone notice that some gearboxes has a psst psst psst....... sound? Similar to the SBSTransit 0405 mercedes gearboxes? Although the mercedes gearbox one can be heard very loud, ZFs can be heard too! Anyone can tell me why? Izzit because of the retarder? Please ! I would really like to know!
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What "psst psst" sound? It is like air releasing? I haven't noticed it yet.Originally posted by Scania N113CRB luver:Anyone noticed that some ZFs lock-up on the first gear, as well as the second gear in some models(all lances)? And also anyone notice that some gearboxes has a psst psst psst....... sound? Similar to the SBSTransit 0405 mercedes gearboxes? Although the mercedes gearbox one can be heard very loud, ZFs can be heard too! Anyone can tell me why? Izzit because of the retarder? Please ! I would really like to know! -
Im not too sure. Notice it carefully, when it changes from 4th to 3rd gear for example, it will have a psst sound. I think it is the retarder at work. When it switches to neutral, it can be heard more clearly. Confirmed not the brakes! The Dennis lances, some LO, some VO3x, some SMRT 0405/0405g had the same sounds!
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This would be the air escaping the retarder system as air is built up to slow the bus down. The retarders are magnets which use a forcefield to slow the engine rpm down. It comes down to variances in gearbox build, some ZFs howl, some don't. I have programmed ZF gearboxes to lock up or not lock up, and alter shift points (ie, what engine rpm to kick up a gear).
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Air? I thought i uses hydraulics? I thought it is a hydraulic retarder. Anyway thanks for the information! I realised that some SMRT Volgren 0405 had been programmed to have no gear lock-ups, is dat true?
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ya. the howling can be heard on the SMRT Volgren 0405, especially when it shifts from 4th to 3rd gear. Sometimes very loud.Originally posted by Windy_hates_B10TLs:This would be the air escaping the retarder system as air is built up to slow the bus down. The retarders are magnets which use a forcefield to slow the engine rpm down. It comes down to variances in gearbox build, some ZFs howl, some don't. I have programmed ZF gearboxes to lock up or not lock up, and alter shift points (ie, what engine rpm to kick up a gear). -
windy are u some kind of mechanic or engineer?
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What do you mean by lock up and not lock up? Is it something to do with why some buses like SBS Merc sound like they have 4 gears but only have 3?Originally posted by Windy_hates_B10TLs:It comes down to variances in gearbox build, some ZFs howl, some don't. I have programmed ZF gearboxes to lock up or not lock up, and alter shift points (ie, what engine rpm to kick up a gear). -
indeed.Originally posted by stooper:What do you mean by lock up and not lock up? Is it something to do with why some buses like SBS Merc sound like they have 4 gears but only have 3?
though the underlying principle behind SBS Merc gearbox is not about torque convertor lock-ups but rather slip gears. -
Hmm... What's the differences in slip gears and lock ups then?Originally posted by ^tamago^:indeed.
though the underlying principle behind SBS Merc gearbox is not about torque convertor lock-ups but rather slip gears.
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Yes, and some 0405 Hispano, and maybe some VO3X, although the VO3X one is positively irritating.Originally posted by Scania N113CRB luver:Air? I thought i uses hydraulics? I thought it is a hydraulic retarder. Anyway thanks for the information! I realised that some SMRT Volgren 0405 had been programmed to have no gear lock-ups, is dat true? -
I am a recruitment consultant. I do part time work at a bus company.Originally posted by SBS9828X:windy are u some kind of mechanic or engineer? -
WRONGOriginally posted by ^tamago^:indeed.
though the underlying principle behind SBS Merc gearbox is not about torque convertor lock-ups but rather slip gears.
The Mercedes W3E gearbox's jerkiness is the result of torque convertor lock ups. -
i think the SMRT's L113CRLs has the loudest gear lock-up whining sound in SMRT fleet! Everytime near my house when CRL passes by i can straight away tell that it is the CRL. It is very distinctive! The VO3x and LO3x is even louder!
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Erm does anyone here prefers ZFs over Voiths?
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No real preference.
But the psst sound, heard before many times, and it goes...
wooooo... (braking), psst!, wooo (then normally will have 'dung' sound as the brakes take larger effect), then psst! brake sound, stop.
Diff ppl got diff sound hor, disclaimer... -
Ya, then the SMRT 0405, gear hub-reduct sound most loud and horrible as I saw...
eeerrrooor, emmmmMMMM(rev 1700-2000rpm), BRI-AO!, deeeee... then it will almost miss a gear and goes 'dung' again to get back to a lower gear.
Some sound treatment eh, I love 0405 sounds! -
Voith on 0405G almost kills the signature sounds that ZF had for these Mercedes pals.
Hub reduct on Voith would just mean...
vroooom, VROOOOOOOOM!, vroooooooommmmm and so on...
ZF, diff story.
erooooorrrr, eeeeeemmmmMMBRI-AO!, errrrooooooorrr....
At least there is that sound! -
Ya this is what i meant, i like this sound especially on the LO3x, very distinctive!Originally posted by jetabt767400:No real preference.
But the psst sound, heard before many times, and it goes...
wooooo... (braking), psst!, wooo (then normally will have 'dung' sound as the brakes take larger effect), then psst! brake sound, stop.
Diff ppl got diff sound hor, disclaimer...
I also like it on the O405G Box. I like it especially on the Volgren 0405 rigid. Air-con very quiet, so can here the drone sound and the "weeeeeeeeoooorrrrr" sound!
I love ZFs! -
All O405s have the same hub-reduction from Mercedes. Hub-reduction is a set of planetary gears located inside the rear axle. Its purpose is to further reduce the number of revolutions coming from rear differential, thus increasing torque. Nothing to do with the gearbox at all. And they definitely don't make such noises stated above.Originally posted by jetabt767400:Voith on 0405G almost kills the signature sounds that ZF had for these Mercedes pals.
Hub reduct on Voith would just mean...
vroooom, VROOOOOOOOM!, vroooooooommmmm and so on...
ZF, diff story.
erooooorrrr, eeeeeemmmmMMBRI-AO!, errrrooooooorrr....
At least there is that sound! -
Yeah, you don't hear the hub reductors clearly when accelerating. You only hear them when the bus is at top gear or when the bus is decelerating.Originally posted by The_Bus_Guide:And they definitely don't make such noises stated above. -
Ya notice that the hub reduction axle is very similar to those used on Actros tractors? New mercedes city buses such as the OC500LE and the Citaro no longer have this axle. They used a newer and a different one.Originally posted by The_Bus_Guide:All O405s have the same hub-reduction from Mercedes. Hub-reduction is a set of planetary gears located inside the rear axle. Its purpose is to further reduce the number of revolutions coming from rear differential, thus increasing torque. Nothing to do with the gearbox at all. And they definitely don't make such noises stated above. -
I am really culeless, but does hub-reduct means kickdown in gear? If not then there is a mix up in my knowledge then, thanks.Originally posted by The_Bus_Guide:All O405s have the same hub-reduction from Mercedes. Hub-reduction is a set of planetary gears located inside the rear axle. Its purpose is to further reduce the number of revolutions coming from rear differential, thus increasing torque. Nothing to do with the gearbox at all. And they definitely don't make such noises stated above. -
Oh by the way, correct me if im wrong. The rear axles used on the Citaros are mand by ZF, known as the ZF portal axles.Originally posted by Scania N113CRB luver:Ya notice that the hub reduction axle is very similar to those used on Actros tractors? New mercedes city buses such as the OC500LE and the Citaro no longer have this axle. They used a newer and a different one.