Bulldozer Geardown

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Design Proposals

single reduction with full axel

sketchup model


Geardown-singlereductionfullaxel.png

Day 1 - Dorkmo

  • Folder of first draft Sketchup Files - [1]

Geardown1.png

Design Review

edit

Further Conceptual Design


edit

Geardown Iteration Day 2 by Dorkmo

Geardown2.jpg

File:Geardown2-36T3020.zip

Further Iteration

Gd15.png

- Download v15 here

Review of Day 2 by MJ

It turns out that the sprocket sizes make the geardown particularly large. So I am looking at Page 82 of Martin Sprocket Catalogue and see that the smallest 100 pitch sprocket that would fit our needs is 10 teeth, Diameter of 4.6". This would give us 25 teeth, Diameter of 10.7", as a possibility - but better yet - go for 3x the reduction - 10 teeth to 30 teeth. If 36 teeth is 15" diameter, 30 teeth is about 13" diameter. So inside the geardown unit, we'd need 2x reduction - or going from 10 to 20 teeth - or 8.6" OD. Thus, a 10" box (1/2" walls) appears to suffice for the geardown unit.

Thus, make first step 3x reduction, and second step 2x reduction- to get the geardown unit to compact size of 10" width. The height would need to extend to whatever geometry would make this fit possible.

We would have to get decent prices on the hubs from whatever source is best. We could compromise to 2.6 reduction for the first step if we use this 26T sprocket and weld our own hub.

proto type 1

Mount based on quick attach module

Chain cover and oil pan

  • 4 parts to cut
    • top in
      2 holes to mount to frame and standoffs
      holes to accomidate both flanges' bolts if necessary
      larger holes around shafts to accomidate bearings
    • bottom in
      holes to accomidate both flanges' bolts if necessary
      larger holes around shafts to accomidate bearings
    • top out
      hole for shaft
    • bottom out
      hote for shaft

Mount DXFs

[2]

Initial Conceptual Design


edit

Design Conditions of Satisfaction

  • Check.pngUses exising Quick Connect Wheel rotor - its shaft output.
  • Check.pngGeardown module is CNC cut from 1/2" steel sheet
  • Notches are made such that the structure can be assembled only one way
  • Mechanism for quick disassembly is included
  • Mechanism for tensioning the chain drive is included
  • Enclosure allows easy replacement of parts
  • Check.pngQuick attachment of wheel onto the output shaft of geardown module is possible
  • Wheel is secured via a keyway
  • Input shaft is 1-7/8" thick, output shaft is 3" thick
  • Standard cold rolled shaft is used
  • Mechanism for retaining axial thrust is included
  • Check.pngGeometry must line up for the connection to Quick Attach Wheel
  • Check.pngGuards protect any exposed chains/sprockets for safety
  • Check.pngMethod of coupling to existing Quick Connect Wheel must be used - via chain drive - while considering geometry of frame a drive components
  • Quick Connect Wheel and Geardown units must be sufficiently stable to maintain chain tension. Tightening mechanism must lock in place.
  • Check.pngReference must be provided to verify existence of off-shelf parts
  • Check.png100 Pitch Chain must be used.
  • Check.pngConcept must show approximate dimensions (+/- 2") of the geardown structure
  • Geardown unit must be no more than 250 lbs in weight

LifeTrac Existing Design

Parts

Preliminary BOM

Qty Part# Source Description Unit price
2 1-215-47-4-C Surplus Center 2-15/16" four bolt flange bearing $60.95
2 1-210-32-4-C Surplus Center 2" four bolt flange bearing $21.95
1 2 GKS-1045-18 Grainger 2" keyed shaft $72.25
1 totally belted 2-15/16" X 30" shaft $163.64
1 100SDS11H amazon 11T QD-SDS $85.17
1 SDS178 grainger 1-7/8" QD-SDS $27.25
1 100BS25-2 mro supply 25T, 2" bore $121.60
1 100BS11-2 mro supply 11T, 2" bore $64.00
1 100BS22-2-15/16 mro supply 22T, 2-15/16" bore $113.27
8 21835 fastenal 5/8" x 2-1/4" carriage bolt $1.75

for design #5 [3]

Sprockets

Notes: practical limit for 100 pitch ~ 36 teeth - or 15" OD - [4]

  • Random shaiskizit - [5]
  • Up to 240 pitch - [6]
  • Martin - [7]
  • Baldor - [8]

80#

  • 1-7/8" bore 20T - [9]
  • 1-7/8" bore 14T - [10]
  • 1-7/8" bore 13T 2.3285" O.R. - [11]
  • 2" bore 13T - [12]
  • 2" bore 22T 3.79" O.R. - [13]

80-3

  • 80-3 sprocket 12T [14]
    stock 1” bore
    cutable to 1-7/8”
    smallest 80-3 sprocket for 1-7/8
  • 60T or 68T tooth available 1:5 or 1:5.6 [15]
    stock 1-1/2
    cutable up to 4-1/4
    QD-F
  • 80-3 14T Q2 MST bushing [16]
    needs Q2 MST 1-7/8 bushing [17] [18]

100#

  • 2" bore dia, 11T, 2.504" O.R. - [19]
  • 26 tooth - OD 11" - $10 - Surpluscenter - [20]
    2517 2. tapered bushing [21]
  • 2.938" bore dia, 16T - $123 - [22]
  • 2.938" bore dia, 25T, 5.3225" O.R. - [23]
  • 2" bore dia, 25T - [24]
  • 36T 3020 taper bushing [25]
    3020 3. bushing [26]
  • 11T, 2" bore - $64 [27]
  • 22T, 2-15/16" bore - $133 [28]
  • 25T, 2" bore - $122 [29]
  • 60T, borable - $306 [30]
  • 60T, taper bushed 3020 - $350 [31] [32]

tapered bushing sets

1-7/8" shaft to 13T 100# sprocket

keyed 1-7/8" to 2012 size tapered bushing
http://www.grainger.com/Grainger/GATES-TaperLock-Bushing-1NJD5?Pid=search
2012 tapered bore, 13T, 2.9105" O.R.
http://www.amazonsupply.com/dp/B00452USMO/ref=sp_dp_g2c_asin

QD bushing sets

26T, QD-E
http://www.amazonsupply.com/dp/B00452UR8O/ref=sp_dp_g2c_asin
1-7/8" to QD-E
http://www.grainger.com/Grainger/TB-WOODS-Quick-Detachable-Bushing-5YLN7?Pid=search


Weld to hub

10T
http://www.amazonsupply.com/martin-roller-sprocket-reboreable-single/dp/B004JXWGV0/ref=sr_1_1?sr=1-1&qid=1370216789&filterBy.size_name=100&filterBy.number_of_teeth=10
weldable hubs
http://www.ggmfg.com/Products/Weldahubs/WELDAHUBS.aspx

Modeling

  • OpenSCAD sprocket designer [38]

how to draw with sketchup [39]

Modeling/Sprockets

sprockets

45T 100# File:45T.dxf

45T 100# HD File:45THD.dxf

  • 1.656836 ftsq
  • 11/16 plate steel = .6875
    • nominal sprocket thickness .692
  • 46.5lbs at 28.05 density

Sourcing Problems

  • 100# chain sprokets hard to find
  • 80# chain sprokets with bore dia above 2" hard to find
  • minimum teeth on 100# sprocket for 3" shaft with 3020 tapered bushing = 28
  • max shaft size for a bored to size 100# sprocket = 2.938
  • available carriage bolt sizes limited:
    1/4, 5/16, 3/8, 7/16, 1/2, 5/8, 3/4
    M5 M6 M8 M10 M12 M16
  • 1-7/8" QD-SDS torque rating is 5,000lbs

budgeting

  • 100-1 sprockets cheaper than 80-3

Links

product examples