Discussion:
Sellick SD-80 Brakes

Serial Number: 70817705S8J-4 Full Model # SD-80 JDS-4
Was wondering if anyone has any info on the brake system in this truck. It is a hydraulic actuated brake pedal(MICO) that goes to what looks like an accumulator,was wondering if this is a wet clutch pack type sytem that is internal to the transmission as there is nothing at any of the wheel hubs. The Parking/emergency hand brake is a caliper/rotor assembly on the driveshaft, the customer says the brakes act weak at times and feel like they drag as if the drum was rusty and the pads were hanging up but as i stated there is no brake assemblies at the wheels.
Any info would be greatly appreciated as far as a hydraulic diagram or a brake section from the manual?
  • Posted 18 Aug 2012 04:56
  • By kevin_t
  • joined 2 Dec'10 - 1,301 messages
  • Pennsylvania, United States
Showing items 1 - 9 of 9 results.
You're missing the point, there was no need to be sarcastic. I've been doing this for 25+ years, have fun with it.
  • Posted 21 Aug 2012 07:25
  • By bigGlittlestar
  • joined 12 Aug'08 - 139 messages
  • United States
Yea bigGlittlestar i am just a idiot,i dont know anything............I have only been a tech for 10+ years and dont know as much as you,so i bow down to your superiority.
  • Posted 20 Aug 2012 19:16
  • Modified 20 Aug 2012 20:05 by poster
  • By kevin_t
  • joined 2 Dec'10 - 1,301 messages
  • Pennsylvania, United States
and apparently as you STATED you dont know what youre doing or looking for I worked for a Sellick dealer for ten years and worked on many of the brake systems on these units and ULTIMATELY there is brake lines and fluid that goes to the brakes that are internal on this unit. So have fun figuring it out but I will tell you what the problem probably is and was fairly common in those. The end clip on one of the clutch pack shaft rings breaks off cutting a gouge in the housing and you get pressure bypassing acting like the brakes are dragging the only way we found it after we found no problems with the brakes was to break the tranny down. So have fun ***.
  • Posted 20 Aug 2012 13:10
  • By bigGlittlestar
  • joined 12 Aug'08 - 139 messages
  • United States
Ok,thanks i will check it out more when i get back to the customer again....Was just curious if anyone had the brakes section of the manual that they could share,and/or a hydraulic schematic
  • Posted 19 Aug 2012 01:40
  • Modified 19 Aug 2012 01:41 by poster
  • By kevin_t
  • joined 2 Dec'10 - 1,301 messages
  • Pennsylvania, United States
Kevin, I can tell you that I have pulled and rebuild an SD100 transmission and there are no internal brake parts. I also reconditioned the brakes on an SG60 and it had a piston that applied pressure to wet brake discs that mounted outboard of the differential housing. On that system, as I recall, it had a Mico master cylinder that you filled with an oil, which had a special spec. Why not lift one drive tire at the time by tilting the mast forward on a block and see if one or both sides appear to be dragging? I would then locate the brake line to each side or bleeder to crack it and see if it has pressure without the brake applied. Maybe the valve is bypassing? Possibly the pushrod is too tight??
  • Posted 19 Aug 2012 01:36
  • By Forkliftt
  • joined 13 Jul'09 - 321 messages
  • Louisiana, United States
Steve
steve at forkliftt dot com
From looking at it briefly today it looks like the brakes are run off the main hydraulic system,is no master cylinder,the brake pedal is a mico hydraulic valve and goes into an accummulator then looks like it goes into the transmission but cant confirm that,i DO know there are NO brake drums or lines on the backside of ALL 4 wheels is what makes me think the brake is a clutch friction plate wet system internal to the tranny but would like a manual section for the brakes on this truck to confirm
  • Posted 18 Aug 2012 13:02
  • By kevin_t
  • joined 2 Dec'10 - 1,301 messages
  • Pennsylvania, United States
Kevin,
I have seen wet brake systems "drag" when incorrect oil has been used in the master cylinder. In your case,this wouldn't apply. Where does the oil that supplies the master cylinder valve flow from? Can you crack a brake line at rest to check for residual pressure?
  • Posted 18 Aug 2012 12:36
  • By Forkliftt
  • joined 13 Jul'09 - 321 messages
  • Louisiana, United States
Steve
steve at forkliftt dot com
as i STATED in my opening post the brakes on this truck are run off of the hydraulic system and the brake pedal is actually a hydraulic foot actuated valve there is no master cylinder...........
  • Posted 18 Aug 2012 09:55
  • By kevin_t
  • joined 2 Dec'10 - 1,301 messages
  • Pennsylvania, United States
Brakes are an internal set up you need to split the front axle housing down into three pieces. you should be able to follow the brake lines from the master cylinder into the center case area of the differential.
  • Posted 18 Aug 2012 07:53
  • By bigGlittlestar
  • joined 12 Aug'08 - 139 messages
  • United States

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