ASME B56.8:1993 pdf download

ASME B56.8:1993 pdf download Safety Standard for Personnel and Burden Carriers
7.3.7 Steering
a)Carriers employing a handwheel or a horizontallever (horizontal motion) or a tiller bar for steering con-trol shall have such controls designed so the carrier willrespond as follows when moving in a forwand direction:movement of the steering control in a clockwise direc-tion shall steer the carrier to the operator’s right.
(b)All steering controls shall be confined within theplan view outline of the carrier or provided with guardsthat protect against injury to the operator during move-ment of the controls, and while passing obstacles, walls,columns. etc.
7.3.8 Travel Controls
a)Travel controls shall be so arranged that the car-rier will not operate unless controls) has been actuatedfor both direction and speed.
()Accelerator, if foot operated, shall increase speedwhen depressing the pedal downward or forward.
(c)Service brakes，if foot operated, shall be ener-gized by depressing the pedal downward or forward.(d)Ifa single foot pedal controls both accelerationand braking,depressing the pedal shall increase speedand releasing the pedal shall apply brakes.
(e) A manually operated device shall be provided todisconnecr all travel control circuits.
(f)If both forward and reverse directions are pro-vlded, direction control shall clearly and durably iden-tify forward and reverse directions.
(g)A parking brake shall be provided.
h)Control pedals and control platfonms that arestood on or engaged by the opcrator’s feet shall havcskid resistant surfaces.
7.3.9 Stability Tests
a) General Test Condirions and Requirements() A test platform shall be used that is rigid,flat,and constructed to be an adjustable slope, single plane(tilt tablc) with a surface finish adequate to prevent slid-ing of the tires.The table surface shall be large enoughto suppon all wheels of the canrier to be tested.
Tire inflation on all wheels shall be in accor-dance with the caier manufacturer’s specifications orrecommendations.
Prior to the addition of test loads, the carrier tobe tested shall be readied to reflect its operating weight
and shall include all accessory items which,when in-stalled, will decrease the stability of the carrier.
(4)The manufacturer’s specified maximum mate-rial load shall be designated as the test load, placed onthe load bed of the carrier, and secured thereto such thatits center of gravity is directly above the geometric cen-ter of the load bed.The height of the center of gravityof the test load above the load bed shall be determinedby Fig.1.
(a) To obtain the proper height of the center ofgravity for the test load from Fig. l,first calculate thebed area of the carrier. With this result. enter the tableat the bottom,read vertically upward to the line identi-fied as the payload which represents the manufacturer’sspecified maximum material load or interpolate betweenthe lines to get an intermediate point. and then read tothe left margin for center of gravity height.
(b) On special purpose carriers designed for un-usual loadings,the maximum load height above the bedshall be specified on the nameplate.This carrier shall betested with a test load having a center of gravity locatedat a point above the carrier load bed that is one-half ofthe maximum specified load height.
(5 The operator or passenger load shall be posi-tioned and secured as follows.
(a)For sit-down carriers,a 200 lb (90 kg)weight shall be secured to each seat，representing theoperator and each passenger as specified. If seats areadjustable,they shall be adjusted to that position rep-resenting the least stable condition in cach test.The cen-ter of gravity of the weight(s) is to be 6 in. (152 mm)above the lowest point of the operator supporting sur-face and 10 in. (254 mm) forward of the seat back. If ascat back is not used, then 10 in. (254 mm) will be mea-sured rrom the position of the back of an actual operatorwhen seated normally on the unit.
b)For stand-up carriers, a 200 lb (90 kg) weightshall be secured at the geometric center of the operalorplatform representing the operator. The center of gravityof the weight is to be 40 in. (1016 mm) above the op-erator platform.
(6Calculated Stabiliry Factors.In order to pro-vide a means for handling everyday stability deteimi-nations, stability factors as related to the tilting platformtests may be ealeutated.These calculations will usuallyvary for each manufacturer’s product and normally takeinto account variations in design,including tires andother deflections,and provide a means for predictingwith reasonable accuracy the stability of carricrs. Tilt-ing platfonm tests are the basis for establishing factorsused in stability calculations. When comparing calcu-lations with actual tilting platfom tests. the actual testresults are to be considered the true measure of stability.