ABCDEFG
1
Test StepProcedurePart SpecsData CollectedVideo LinksPicture LinksComments
2
META
3
DATE - Wed Oct 23, 2013
4
PERSON - Marcin Jakubowski, Dan Belamy
5
GENERAL
6
Hydraulic Pump Pressure3000 PSI pump on power cube
7
Horsepower Used 1 power cube, 27 hp drive
8
valve used, 4600psi rated, working pressure relief max at 1450psihttps://www.surpluscenter.com/Hydraulics/Hydraulic-Valves/Directional-Control-Valves/6-SPOOL-16-GPM-WALVOIL-JOYSTICK-BACKHOE-HYD-VALVE.axd
9
10
SYSTEM PRESSURES2500 psi
11
theoretical 6-spool joystick valve pressurefrom websitestarted with preset, 1160 PSI
12
actual 6-spool valve pressuremeasured
13
loader arm pressurePressure gauge on left cylinder rod-end port; same result on bottom port

http://www.surpluscenter.com/Hydraulics/Hydraulic-Cylinders/Double-Acting-Hydraulic-Cylinders/2X32X1-25-DA-HYD-CYL-1-PINS-HVY-DUTY-CROSSTUBE.axdBad design on loader arms. 2" cylinders currently do not lift backhoe off the ground. Increasig loader arm pressure for lift.
14
loader arm pressure required for lift of backhoe off the ground
15
typical curling pressure in curl cylinder
16
typical stick pressure from backhoe in fully extended position
17
typical boom pressure during lift of boom
18
typical pressure of leg cylinders with boom in upright position
19
TESTING PROCEDURE
20
FREE
21
increase system pressure on loader arm cylinders (3500PSI max), with system pressure at 3000 PSI max.point at which liftoff is attained - ____ PSI
22
move tractor into position out of workshop
23
extend backhoe all way out, measure length at full extension
24
curl bucket, measure extended angle
25
curl bucket, measure retracted angle
26
measure maximum angle between boom and stick
27
measure minimum angle between boom and stick
28
swing backhoe side to side, measure angleextend fully to one side slowly, then to the other
29
MEASUREMENTS UNDER PRESSURE
30
qualitative ability of backhoe to drag tractor on the ground - bucketallow tractor to freewheel, and observe if backhoe drags entire tractor solely by curling the bucket cylinder. Measure pressure of bucket cylinder.
31
qualitative ability of backhoe to drag tractor on the ground - stickWith bucket in fixedstickgrabbing position, move the boom to observe if it drags the tractor forward in freewheeling mode. Measure pressure at which this happens.
32
max pressure of bucket, extended position of boom and stickDo not allow tractor to freewheel, use stabilization by putting the backhoe firmly on the ground. Observe pressure that bucket exerts when digging the soil. Observe rubustness of digging - if digging is complete (full bite) versus partial bite as backhoe moves up without digging
33
max pressure of bucket, optimum digging positionPosition bucket at 60 degrees to the ground (optimal beginning of dig), while stabilizing backhoe. Observe pressure at which digging occurs. Observe robustness of digging.
34
set relief of side-to side cylinder at 1500 PSIUse hydraulic pressure gauge inline with exit ports of side-to-side cylinder lever. Move cylinder to limit and observe the reading on the pressure gauge once bypassing occurs at limit. If tractor stalls, decrease setting of cushion valve, and observe results. To adjust cushion valve - do both sides of the cushion valve at a time.
35
pressure for side-to-side cylindersSet relief of side-to-side cylinder cushion valve at 1500 PSI. measure pressure upon motion of backhoe under low tractor power, and observe the spike attained upon release
36
pressure of curling action of bucket from full extended positionextend backhoe fully out and down on ground; curl bucket, observe pressure on hydraulic guage connected inline with curl cylinder
37
digging result - compacted soilobserve if backhoe lifts off ground or digs
38
decrease angle of stick to comfortable digging positionobserve pressure of boom cylinder and stick cylinder
39
DESTRUCTIVE TESTING LIMITS PROCEDURE
40
obtain all baseline data above
41
measure lateral force limitsmeasure pressure required for structures to bend or break when hitting somothing laterally instead of using backhoe up and down. Increase lateral pressure of side to side cylinders up to point where sudden left-right motion breaks the side to side turning cylinder mounts. Observe pressure at which this failure occurs. Goal is to have that limit occur at 2x the normal operating pressure of the backhoe.
42
measure bending force limits -increase pressure of stick cylinder
43
PERFORMANCE AND SPECIFICATIONS
44
Side to side motion angle
45
vertical height to top of boom (with backhoe on ground and not elevated with feet)
46
length of backhoe at full extension on the ground to tip of bucket edge
47
angle rotation of stick
48
angle rotation of bucket
49
max dig depth, theoretical
50
max dig depth, observed
51
ISSUES
52
stick cylinder is too longshaft bends around radius of rotation if extended too far
53
legs are looseleg to leg upright attachment needs to be stiff, precision bushings needed
54
leg uprights and leg cylinders too tallleg uprights are too tall, should be shortened by 16"
55
power beyond valves missing in tractor valvesthis is an issue on tractor, not backhoe per se
56
57
58
HUMAN FACTORS/USABILITY
59
general human factorsdifficult to enter tractor cab with valve mounted in front
60
operation comfortperson sits in tractor seat comfortably
61
hydraulics designcurrently, one lever must be held or bungeed at all times to activate backhoe valve
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100