Below are the first 10 and last 10 pages of uncorrected machine-read text (when available) of this chapter, followed by the top 30 algorithmically extracted key phrases from the chapter as a whole.
Intended to provide our own search engines and external engines with highly rich, chapter-representative searchable text on the opening pages of each chapter.
Because it is UNCORRECTED material, please consider the following text as a useful but insufficient proxy for the authoritative book pages.
Do not use for reproduction, copying, pasting, or reading; exclusively for search engines.
OCR for page 10
10
and KUAB 240 are available as single-axle trailer-mounted ˇ Giving operators an ownership stake in the FWD
FWDs or as vehicle-mounted FWDs. equipment they operate
ˇ Overhauling the equipment when needed
Maintenance Practices A few SHAs reported that their FWDs have not yet needed
"significant maintenance."
Most SHAs perform regular maintenance on their FWD
equipment and their tow vehicles. These maintenance activi- Manufacturers' Recommendations
ties are separate from calibration and can include mechani-
cal lubrication, replacement of consumable parts, leak FWD equipment manufacturers generally follow LTPP
repair, cleaning, and other activities that keep the mechani- guidelines for equipment maintenance and offer mainte-
cal devices in working order. nance services on the equipment they sell. For example, Carl
Bro supplies a comprehensive maintenance list to its clients,
State Highway Agency Falling Weight which breaks down maintenance activities by individual
Deflectometer Maintenance FWD component. In their preventative maintenance check-
list, Dynatest recommends that brake operation, hand brake
Although most SHAs do not have a written FWD mainte- pump, load plate lubrication, tires, and belts be inspected on
nance plan (Appendix B, Question 7), maintenance activi- a daily basis; their FWD equipment checklist is summarized
ties are performed by SHA personnel. FWD equipment and in Table 4.
tow vehicle maintenance is performed by SHA employees
among 87% of survey respondents (Appendix B, Questions In addition to providing JILS-FWD maintenance ser-
910). Seventeen percent of SHAs reported that they fol- vices, Foundation Mechanics, Inc.'s maintenance personnel
low the manufacturer's guidelines for regular maintenance. are able to log into their clients' JILS-FWD computers over
Those who did not follow the manufacturer's guidelines usu- the Internet to review files and perform diagnostic tests.
ally stated that maintenance activities are done when needed.
Twenty-five agencies (listed in Appendix B, Question 11) KUAB offers a preventative maintenance program as an
provided other suggestions on keeping their FWD equip- option with their FWDs, which includes cleaning, inspec-
ment in working order, including the following (Appendix tion, and calibration. The procedures typically take between
B, Questions 8 and 11): three and four weeks to complete and are done by KUAB
personnel at their Savoy, Illinois, facility.
ˇ Cleaning the sensors and holders with an emery cloth
ˇ Storing FWD equipment and vehicles in a heated Merits of Falling Weight Deflectometer Versus
garage when not in use Other Nondestructive Testing Devices
ˇ Bleeding hydraulic lines annually
ˇ Following a brief maintenance checklist before depart- The Missouri DOT (MoDOT) detailed the merits of FWD
ing for a job usage in an undersealing study. Before employing FWDs to
ˇ Including maintenance activities when FWDs are detect voids, MoDOT used to test load transfer efficiency
calibrated (LTE) by the "proof-rolling method." A dump truck was
filled to give a rear-axle load of 80 kN (18,000 lbf), and its
TABLE 4
DYNATEST RECOMMENDED MAINTENANCE ACTIVITIES AND FREQUENCIES
Frequency Activities
Check brake operation, check hand brake pump for free movement, check load plate for lubrication, clean
Daily, or as required
clamping magnets/disks/springs.
Tire pressure (approx. 32 psi), lug nuts tight (7590 ft-lb), check breakaway feature (actuator), check brake
Weekly lock operation, inner catch parts lubricated with Teflon, external weight guides lubricated with Teflon,
lubricate SD foam guides with silicone spray, check/refill battery level, clean infrared/air sensors.
Check brake fluid level (DOT type 3 only), check rubber stabilizers for tightness, nuts and bolts tight, R/L
cable checked for bends/breaks, check deflector holderstips tight, clean sensor cables with soapy water
Monthly
only, check charging system connections, coat terminals with corrosion inhibitor, check hydraulic fluid
level, clean/inspect electronic connections, perform relative calibration, wash equipment.
Annually Change hydraulic fluid, change hydraulic fluid filter, perform reference calibration.
Source: DYNATEST.
OCR for page 11
11
rear tire was placed 1 ft past a transverse joint between two ˇ Less manpower is required.
slabs. Gauges then gave the deflections generated by the ˇ Lanes are closed for less time.
load on each slab. When measured, LTE is less than 65% ˇ "No influence of shoulder movement to apparatus."
and loaded side deflections were greater than 0.44 mm ˇ Dynamic FWD impulse loads provide a more realistic
(17.5 mils), the slab was undersealed. FWDs are preferred simulation of truck movements.
over the proof-rolling method, for the following reasons ˇ Multiple load levels are possible.
(Donahue 2004):
