BM-3 pendulum coefficient of friction tester uses: This instrument is the latest product of Hebei Province, Hongyu equipment Co., Ltd. is mainly used for high-grade highways, urban roads and the airport runway skid resistance testing. Applies to the road surface friction coefficient of determination, can be lowered then. The instrument is convenient debugging, simple operation, accurate test data, greatly enhanced stability, and can be used indoors and outdoors, is an indispensable one of the testing equipment in the construction of high-grade highways, and other special equipment.

   BM-3 pendulum coefficient of friction tester is a dynamic pendulum impact instrument. It is based on "put the potential loss equal to the arm end of the rubber sheet sliding on the road, to overcome this basic principle of the work done by the road surface friction" from the development.

BM-3 pendulum coefficient of friction tester main technical parameters:
Swing weight: 1500g ± 30g
Placed center of gravity moment: 410mm ± 5mm
Rubber sheet on the road forward static pressure: 22.2N / 2263g
Placed in a rubber sheet end from the swing-foot distance: 508mm
Placed on the road sliding length: 126mm
Dimensions: 700 × 360 × 700mm
Weight: about 12kg
Swing free from the tilt 5 degrees to lay down the number of swing stop should be at least 70 times.

Fourth, the BM-3 pendulum coefficient of friction tester apparatus main part of the swing part of the rack part.

 

1,2 - tighten the handle; 3 - Lifting the handle; 4 - Release the switch; 5 - knuckle screw cap; 6 - adjusting nut; - needle reed or Felt

8 - pointer; 9 - connecting nut; 10 - leveling bolt; 11 - base; 12 - hinge; 13 - bubble level; 14 - clasp;

15 - positioning screws; 16 - Lifting the handle; 17 - counterweight; 18 - and tighten the nut; 19 - slippery block; 20 - rubber sheets; 21 - Anti-slip screw

 

1,: by the T-leg leveling screws and bubble level. Tone from the instrument level, supporting role.

2, column: column, the lifting mechanism, the guide bar and instrument handles. For the location of the lift and fixed Rocker.

3, release the switch: installed at the switch on the cantilever. Used to maintain the horizontal position and release of the pendulum to swing down the role.

4, the composition of the Rocker: by tightening the handle, the pendulum shaft, steering knuckles, bearings, etc., from the links placed, fixed position, to ensure free and swinging in the swing plane.

5, showing the number of system: consists of pointers, felt ring, flange, tighten the nut and the dial pointer directly indicates the coefficient of friction values.

6, the pendulum: the upper and lower joints, pendulum, spring, lever Department of lifting handle, shell, slippery block and sheet rubber composition. Its swing center of the required torque and the required pressure on the road itself before and after, left and right torque balance, which is a measure road surface friction coefficient of the scale.

BM-3 pendulum coefficient of friction tester test procedure

1, the choice of site: scooter direction in the test sections, the revolver round track, select a representative of five points, each measuring point a distance of about 5 ~ 10m from the pavement edge should not be less than 1m.

2, instrument leveling:

The instrument placed in the measuring point and the pendulum swing direction and the directions of traffic.

② Turn the leveling screws and bubble level center.

3, zero:

（1） relax the fixed handle, turn the lift handle, so put the rise and can swing freely, then tighten the handle.

（2） will be placed to the right movement, press the release switch. Release the clasp into the switch slot, and in the horizontal release position, then release the switch is released, the pointer should be released to close to dial the pin piece.

（3） press release switch, swing to the left movement, and promote the pointer upward movement, when placed to achieve the maximum home after the whereabouts of the pendulum with his left hand to catch the pointer should refer to zero. If not refer to zero, the adjusting nut slightly tighten or relax the felt circle. Repeat this operation until the pointer refers to zero.

4, calibration slide length:

（1） with a brush to remove loose particles and debris on the road in the swing range

（2） to put the free-hanging, outside swing parallel to the direction of the rubber sheet to set the standard foot （126mm） to relax the tightening handle, turn the lift handle. The pendulum slowly decline, when new to the road of the rubber sheet on the slippery block, to lift the lifting handle the slippery block increased, the pendulum moves to the right and turn the lift handle to put down some distance, and then put down the lifting handle to put slowly move to the left until the edge of the rubber sheet is just exposure to the road, one end is 126mm foot, and then hand to lift the lifting handle, and the slippery block lifted up and placed to continue to move to the left, put down the lift handle, then put the slowly moving to the right edge of the rubber piece once again contact with the road. Rubber sheet twice the distance of the point of contact with the road surface should be 126mm （slip length）. Do not meet the 126mm rotating lifting handle, and then repeat the above steps for the coarse. In line with 126mm after tighten the fastening handle, and then corrected again, slide the length does not meet the standard, raise or lower the front of the instrument base leveling screws to correct, but to be leveling bubble level. Sliding length to meet the requirements. Thereafter, will be placed in a horizontal release position.

Measured: water poured the pavement, scraping with a rubber brush to wash away the mud, and then watering and press the release switch, placed on the road over the pointer to indicate the road surface friction coefficient （typically the first time to record）. Catch the pendulum when the pendulum to swing back, with his left hand, right hand lift the lifting handle the slippery block increases, the movement of the pendulum to the right and press the switch, put a long loop into the release switch, and put the needle allocated to tight rely on dial-pin piece, repeat the determination of five （in each case the sprinkler）, a record of each value. Five values ​​not more than three units （instantly dial a cell half） the difference is greater than three units, you should check the causes, and repeat the above operation, to meet the provisions of the requirements so far.

6, determination of results:

（1） each measuring point with the friction coefficient of five determination of the average of the readings on behalf of the measuring point, and the friction coefficient of the average of five points, on behalf of the determination of sections of the friction coefficient.

（2） determination of reading, that is, the pointer on the dial readings （the "put value"）, divided by 100 is the road friction coefficient. : Put the value 33, the friction coefficient is 0.33.

7, BM-3 pendulum coefficient of friction tester note:

（1） due to the road surface friction coefficient is influenced by the effects of season and temperature, it should record the test date and the temperature of the wet pavement.

（2） The test sections should describe the type of pavement structure, appearance and useful life.

（3） When the return swing to the left swing, be sure to hand to catch the pendulum in order to avoid damage to the slippery blocks and pointer.

（4） should not be within the effective range of rubber sheet sliding on the slippery block of convex and concave, so as not to affect the measured values.

（5） Calibration slide the length should be just a rubber sheet contact with the road shall not be by the power of the pendulum slide forward, slide length is too long to avoid calibration.

（6） the friction coefficient changes along the cross-section of the highway. Usually primary and secondary road, roadside. Should be selected to reflect the most unfavorable conditions of the test sections of the friction coefficient is small, more frequent brake position. Along the directions of traffic revolver wheel track at.

（7） on the slippery block, rubber films, should be tested on a dry road several times before. The long edge of sheet rubber abrasion shall not exceed 3.2mm, and the short side shall not exceed 1.6mm （see Figure 2）. Otherwise they should be replaced with new rubber sheet. In addition, the rubber sheet for Oil Pollution. The effective use of rubber sheet for one year. A year later, regardless of whether the use, shall make the determination to use. Rubber aging, elasticity, hardness change, and affect the test results.

Figure 2, the maximum wear of the rubber sheet degrees

 

Six, annex

a） the watering can （a）;

b） the rubber sheet （four）;

c） standard ruler （a）;

d） The rubber brush （a）;

e） tripod （a）;

VII Appendix

BM-3 tilting friction coefficient of determination of the calibration of the instrument tilting instrument:

1, the weight of the pendulum - relax the connecting nut of the pendulum rod and steering knuckle, remove from the instrument equipped with a slippery swing. Weighed accuray to g, （should be consistent with the 1500g ± 30g）.

2, center of gravity - equipped with a slippery block placed center of gravity is determined by the location will be put placed on the knife-edge. Equilibrium point of the test position, connecting nuts, should be fixed on the arm remote to get the balance point, precession or spin out of balance hammer until the pendulum shell edge level and balance position to make a mark.

3, the distance from the swing center to center of gravity - the pendulum re-installed in the instrument and remove the screw cap of the steering knuckle. The distance measured from the swing center （bearing nut center） to the center of gravity, accurate to the mm （410mm ± mm） should be consistent. If differences in the center of gravity placed on the blade to change the torque adjustment nut position, necessary, increase or decrease the torque adjustment nut number, but shall comply with the requirements of （1） and （3）, so that the pendulum balance meet the torque requirements.

4, the pressure calibration:

（1） will be placed from the instrument to remove the slippery block of rubber sheet and put the shell weeks board parallel. Ensure that the slippery block around its own axis of rotation, the shaft runout is greater than 0.2mm.

（2） the pressure calibration of the balance placed in the test stand, leveling so that the pointer refers to. Tripod placed on the right side of the rear of said disk. Pendulum instrument on the tripod on the folder block the pendulum on the column, so that the rubber sheet at the right, said disk Ministry and pressure 3 ~ 5mm, said disk plus 1g weight on the left, the balance stability （this when the balance pointer to the right side）. Adjust the instrument base leveling screws so that the pointer to align the right side of 20mm, and pay attention to maintaining the standard foam center.

（3） in the left side of the pan and then add the calibration weight （2263g）, the pointer should return to zero. If the pointer does not return to zero, said the pressure of the rubber sheet on the road is too large （partial right of the pointer） or too small （the pointer to the left side）. Remove the calibration of the pendulum, insert the spring lead tank with a screwdriver, tighten or unscrew the spring tension adjustment nut so that the pointer back to zero. You should pay attention to grip the pendulum, tighten and relax regulator section nut Buzhi Yu artificial symmetry disk load. Then, re-checking the pressure, until the center of the pointer until the weight is coupled with calibration. （You can use the electronic scale calibration）