Microtractor Part Sourcing
Contents
Overview
Part Sourcing for the Microtractor. Much design work has been merged into the Power Cube.
Engine
Sourcing
- 14 hp 2 cylinder engine no starter $975
- 11 hp 1 cylinder generator $899.00
- 13 hp 1 cylinder silent $1300
- 13 hp $695 GAS
- 23 hp water cooled diesel engine with radiator $1000 - $1349
- 62 hp 4 cylinder tractor $1828
- 65 hp 4 cylinder tractor $710
- 40 hp 3 cylinder $1500 - $2300
- 35 hp 3 cylinder tractor $1185
- 90 hp 4 cylinder diesel 2000 vw beetle $2000
- 11 hp 1 cylinder $400
- 13.7 hp 2 cylinder $666
- Perkins 402C 13.7hp 2 cylinder Same as above, asked for quote 3/5/09 talked to jeff
Power Cube (MicroTrac engine cube) Details
- The coupler halves and spider are shown in the pictures, from McMaster Carr page 1157
Power Calculations
Pump
Hydraulics Calculations from [1]
- From [2] - Pumping = 1 Hp = 1 GPM x 1500 Psi - (linear relationship i.e. 2 GPM @ 1500 Psi = 2 Hp)
- For the above pump, 14.2 gpm with 3000 psi indicates 28.4 hp requirement
- Hp to drive hydraulic pump = Psi x GPM / 1714
- For the above .97 cu in pump, 3000*14.2/1714 = 24 hp
- If we run at 2200 psi => 18 hp required
- For .86 cu in pump, need 3000*12.6/1714 = 22 hp
- For the same with 2500 psi, 18.3 hp
Power Available
- Assuming 85% pump efficiency, we have 17.5*.85=14.8 hp power available to the machine
Wheel Motor Calculations
- 32 cu in wheel motor: 20 gpm, 5170 in lb torque, 145 rpm
- Using 12 gpm, 5170 in lb torque, at 87 rpm - uses 7 hp of the engine
Spider Torque Rating
The Hytrel coupler spider has a 401 in lb torque rating. This is at 3600 rpm. If this pump is driving a hydraulic motor at 87 rpm (wheel motor at 12 gpm fluid flow, at its rated torque), what would be the maximum torque that the 87 rpm could have? 401*3600/87 = 16600 in lb. That is well within the 5130 in lb torque of the wheel motor. Coupler spider will hold up.
Engine
Wheels
- one set of drive wheels in the middle balanced with the engine so the Microtrac can be rotated easily, with a motor on the side
- doubled up for traction
- have support wheels on the back sides so it doesn't tip easily
- drive wheels the same as lifetrac, 30" high 10" wide
Resource Map
Reviewers:
- http://www.tractorbynet.com/forums/build-yourself/140170-homemade-modular-hydraulic-engine.html
- No response as of 4.28.09
- http://forums.hydraulicspneumatics.com/eve/forums?a=tpc&s=4721063911&f=8641063911&m=74110526&r=74110526#74110526
- Useful response, including hydraulics primer, Mr. Hanson's contact as a consultant, etc.
- The response claims need for 30 hp if we want 15 gpm at 2200 psi. We have 12 gpm at 2500 psi.
- CadTrac uses 16 gpm pump and 18 hp engine, at 2000 psi for 1/2 of the flow (to wheels) and 1000 psi to rest of flow (loader)
Coupler info:
- http://www.lovejoy-inc.com/uploadedFiles/Catalogs/jw.pdf
- http://www.ohiobelting.com/pdfs/lovejoycplg.pdf
Notes
- On calculations (right picture) - formula for horsepower to drive pump (with 1714 factor) includes the efficiency of the pump (about 85%)
