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1. In a safe location, chock the wheels and release the spring . preventing in success found have owner-operators and fleets Many 1.Many In afleets safe location, and owner-operators chock the wheels have and found release success the spring in preventing brakes. preventing in success found have owner-operators and fleets Many brakes. spring the release and 1.wheels Many Inthe afleets safechock location,and owner-operators chock location, thesafe a wheels In have1. and found release success the spring in preventing brakes. brakes. spring the release and wheels the chock location, safe a In 1. Many fleets and owner-operators have found success in preventing 2. Bring the air pressure to 90 to 100 psi (620 to 690 kPa), then turn each at measurements stroke chamber brake tracking by violations 2.violations Bring the by airtracking pressure brake to 90 chamber to 100 psistroke (620 measurements to 690 kPa), then at each turn each at measurements stroke chamber brake tracking by violations turn then kPa), 690 to (620 psi 100 2.violationsto Bring 90 to the by airtracking pressurepressure air brake tothe 90 chamber to Bring 1002. psistroke (620 measurements to 690 kPa), then at each turn turn then kPa), 690 to (620 psi 100 to 90 to pressure air the Bring 2. violations by tracking brake chamber stroke measurements at each off the engine. This programs. Air maintenance Brake periodic their of part as wheel-end wheel-endoff the engine. as part of their periodic maintenanceBrake programs.Air This This programs. maintenance periodic their of part as wheel-end Air BrakeBrake Air wheel-endoff the engine. as part of their engine. periodicthe off maintenance programs. This engine. the off Air Brake wheel-end as part of their periodic maintenance programs. This See measured. is it time each stroke pushrod recording involves involves recording pushrod stroke each time it is measured. See See measured. is it time each stroke pushrod recording involves involves recording pushrod stroke each time it is measured. See involves recording pushrod stroke each time it is measured. See 3. Identify the size and type of each brake chamber. See Table 1. Pushrod Stroke 2. Table 3.Table Identify 2. the size and type of each brakeStroke chamber. See Table 1. Pushrod 2. Table PushrodStroke Stroke1. Table See Pushrod chamber. brake 3.Tableeach of Identify 2. type the and size andsize typethe of each Identify brake3. chamber. See Table 1. 1. Table See chamber. brake each of type and size the Identify 3. Pushrod Stroke Table 2. 4. Scribe the pushrods. The Commercial Vehicle Safety Alliance (CVSA) is 4. Scribe the pushrods. The Commercial is Vehicle Safety (CVSA) Alliance Alliance (CVSA) Safety is Vehicle Commercial The 4. Scribe is the pushrods. (CVSA) pushrods. Alliance the Scribe Safety 4. Vehicle Commercial The The Commercial Vehicle Safety Alliance (CVSA)pushrods. the is Scribe 4. o xml, osdr tuktatr ih ye 4 hmes on chambers 24L Type with -tractor a consider example, For For example, consider a truck-tractor with Type 24L chambers on on chambers 24L Type with truck-tractor a consider example, For For example, consider a truck-tractor with Type 24L chambers on For example, consider a truck-tractor with Type 24L chambers on 5. Fully apply and hold the brakes. 5. Fully apply and hold the brakes. 5. Fullybrakes. applythe andhold holdand the apply brakes. Fully 5. brakes. the hold and apply Fully 5. a nonprofit association comprised of local, state, the in limits WhyStroke axles. is drive it the so on important? 30LS Type and axle steer the the steer axle and Type 30LS on the driveimportant? axles. Strokeso it limits is in the Why athe nonprofitin limits Stroke association axles. state, drive the comprised local, on of 30LS Type oflocal, and comprised axle state, steer the association Why nonprofit isa it soimportant? important?so it is Why the steer state, axleand local, of Type 30LS on comprised the drive axles. association Stroke limits in nonprofit thea a nonprofit association comprised of local, state, Why is it so important? the steer axle and Type 30LS on the drive axles. Stroke limits in the 6. Measure the pushrod stroke. provincial, territorial and federal commercial motor inches, 1/2 2 and inches 2 are 30LS Type and 24L Type for regulation 6.regulation Measure for the Type pushrod 24L and stroke. Type 30LS are 2 inches and 2 1/2 inches, provincial, inches, 1/2 2 territorialand inches 2 andare motor federal 30LS Type commercial and commercial 24L Type for motor federal and regulation territorial provincial, 6.regulation Measurestroke. motor for the Type pushrodpushrod 24Lthe and stroke. commercial Type30LS Measure federal 6. are and 2 inches and territorial 2 1/2 inches,provincial, provincial, territorial and federal commercialstroke. pushrod the motor Measure 6. regulation for Type 24L and Type 30LS are 2 inches and 2 1/2 inches, . Confirm the pushrod stroke is within regulatory limits. Do not use vehicle safety officials and industry representatives. respectively. .respectively. Confirm the pushrod stroke is within regulatory limits. Do not use vehicle safety officials and industry representatives. representatives. industry and respectively. officials safety vehicle use not Do limits. regulatory within is .respectively. Confirm stroke thepushrod pushrod representatives. the stroke industry Confirm is and within. regulatory officials limits. safety Do notvehicle use use vehiclenot Do safety limits. officials regulatory within and is industry stroke representatives.pushrod the Confirm . respectively. rated stroke. See Table 1. The Alliance aims to achieve uniformity, compatibility rated stroke. See Table 1. The Alliance aims to achieve uniformity, compatibility compatibility uniformity, achieve to aims Alliance The rated1. stroke.Table SeeSee compatibility Table 1.stroke. uniformity, rated achieve to aims Alliance The The Alliance aims to achieve uniformity,1. Table compatibilitySee stroke. rated and reciprocity of commercial motor vehicle recorded measurements stroke pushrod shows below table The The table below shows pushrod stroke measurements recorded and recorded reciprocity measurements of commercial vehicle stroke pushrod motor motor shows below vehicle table commercial The of reciprocity and The table vehicle below shows motor pushrod stroke commercial of measurements reciprocity recordedand and reciprocity of commercial motor vehicle The table below shows pushrod stroke measurements recorded ntre cain.Nt h ice etisso n baea the at brake one show entries circled the Note occasions. three on on three occasions. Note the circled entries show one brake at the the at brake one show entries circled the Note occasions. three on on three occasions. Note the circled entries show one brake at the on three occasions. Note the circled entries show one brake at the Use this table to determine the stroke limit in the regulation inspections and enforcement by certified inspectors Use this table to determine the stroke limit in the regulation inspections and enforcement inspectors by certified certified by inspectors enforcement and inspections regulation the in limit stroke the Use this table determine inspectors to to determine table certified by this the strokeUse limit enforcement in and the regulationinspections inspections regulation the and in enforcement limit stroke the by certified determine to inspectors table this Use corresponding to the chamber size and type (standard or long stroke the exceeding another and soon) service need will (it limit regulatory correspondingregulatory limit to (it the will chamber need service size and soon) type and (standard another or exceeding long stroke the the exceeding another and soon) service need will (it limit regulatory stroke long or (standard type and correspondingregulatorysize limitchamber to (it the the willto chamber need service size and soon)corresponding type and (standard another or exceeding long stroke the stroke long or (standard type and size chamber the to corresponding regulatory limit (it will need service soon) and another exceeding the design) for each brake on the vehicle. dedicated to driver and vehicle safety. Our mission can table This serviced). be must and violation a is (it limit regulatory design)regulatory for limiteach (itbrake is a onviolation the vehicle. and must be serviced). This table can dedicatedcan table This to driverserviced). andbe vehiclemust mission and Our safety.violation a is safety. Our(it mission limit vehicle and regulatory driver to dedicated design)regulatoryvehicle. the for limiteachon mission (itbrake Our brake is a onviolation each the safety. for vehicle. and must vehicle design) be and serviced). driver to This table candedicated dedicated to driver and vehiclevehicle. safety.the on Ourbrake mission each for design) regulatory limit (it is a violation and must be serviced). This table can is to improve commercial motor vehicle safety and combination. or vehicle a in axles all for account to expanded be be expanded to account for all axles in a vehicle or combination. is to improve combination. commercialor and vehicle a in motor safety axles all vehiclefor vehicle account safety to motor andexpanded be commercial improve to is be expanded and to safety account for vehicle all axles motor in a vehicle or commercial combination. improve to is is to improve commercial motor vehicle safety and be expanded to account for all axles in a vehicle or combination. uniformity throughout Canada, Mexico and the uniformity throughout the Canada, and Mexico Mexico and Canada, the throughout uniformity the and Mexico Canada, throughout uniformity uniformity throughout Canada, Mexico and the Table 1 Table 1 Table 1 1 Table 1 Table United States by providing guidance and education 2 Table Table 2 United States by providing education guidance and and education guidance 2 Table providing by States United Table 2 education and guidance providing by States United United States by providing guidance and education Table 2 TYPE CHAMBER SAE J2899 OUTSIDE MANUFACTURER REGULATION TYPE CHAMBER SAE J2899 OUTSIDE MANUFACTURER REGULATION REGULATION MANUFACTURER TYPEOUTSIDE CHAMBERJ2899 SAE SAE J2899 OUTSIDECHAMBER TYPE MANUFACTURER REGULATION REGULATION MANUFACTURER OUTSIDE J2899 SAE CHAMBER TYPE SIZE MARKING MARKING DIAMETER RATED STROKE STROKE LIMIT to enforcement, industry and policy makers. For more Type Type Type Type Type Type Size: Chamber SIZE MARKINGChamber Size: MARKINGType DIAMETERType Type RATEDType STROKE TypeSTROKE LIMITType to enforcement,Type Type industryType more Type and For policyType makers.Type makers. Size: For policy moreChamber and industry enforcement, to LIMIT STROKE STROKE RATED SIZEDIAMETER MARKINGChamber more For MARKING Size: MARKINGType makers. DIAMETERMARKING Type policy and SIZE Type RATEDType industry STROKE TypeSTROKE LIMITType enforcement, to to enforcement, LIMIT STROKE STROKE industryRATED and policyDIAMETER makers.MARKING For moreMARKING SIZE Chamber Size: Type Type Type Type Type Type 6 None A 4 1/2” (115 mm) 1 1/2” (38 mm) 1 1/4” (32 mm) information, visit www.cvsa.org. 30LS 30LS 30LS 30LS 24L 24L 6 None24L A 4 1/2”24L (115 mm)30LS 1 1/2”30LS (38 mm)30LS 1 1/4” (3230LS mm) information,30LS 30LS visit30LS www.cvsa.org.30LS 24L 24L www.cvsa.org. visit information, mm) (32 1/4” 1 mm) (38 1/2” 1 mm) (115 1/2” 6 4 None A 24L A 41/2” None 24L (1156 mm)30LS 1 1/2”www.cvsa.org. 30LS (38 mm) visit 30LS 1 1/4” (3230LS mm) information, information,mm) (32 1/4” 1 visitmm) (38 www.cvsa.org. 1/2” 1 mm) (115 1/2” 4 A None 6 24L 24L 30LS 30LS 30LS 30LS 9 None B 5 1/4” (133 mm) 1 3/4” (44 mm) 1 3/8” (35 mm) 1/2” 2 1/2” 2 1/2” 2 1/2” 2 2” 2” Stroke Regulation 9 NoneRegulation Stroke 2” B 5 1/4” 2” (133 mm) 2 1/2” 1 3/4” 2 (44 1/2” mm) 2 1/2” 1 3/8” (35 2 mm) 1/2” 1/2” 2 1/2” 2 1/2” 2 1/2” 2 2” 2” Stroke Regulation mm) (35 3/8” 1 mm) (44 3/4” 1 mm) (133 1/4” 9 5 NoneRegulation B Stroke 2” B 51/4” None 2” (1339 mm) 2 1/2” 1 3/4” 2 (44 1/2” mm) 2 1/2” 1 3/8” (35 2 mm) 1/2” mm) (35 3/8” 1 mm) (44 3/4” 1 mm) (133 1/4” 5 B None 9 Regulation Stroke 2” 2” 2 1/2” 2 1/2” 2 1/2” 2 1/2” 12 None B 5 11/16” (144 mm) 1 3/4” (44 mm) 1 3/8” (35 mm) Limit: 12 NoneLimit: B 5 11/16” (144 mm) 1 3/4” (44 mm) 1 3/8” (35 mm) Limit: mm) (35 3/8” 1 mm) (44 3/4” 1 mm) (144 11/16” 12 5 NoneLimit: B B 511/16” None (14412 mm) 1 3/4” (44 mm) 1 3/8” (35 mm) mm) (35 3/8” 1 mm) (44 3/4” 1 mm) (144 11/16” 5 B None 12 Limit: 16 None D 6 3/8” (162 mm) 2 1/4” (57 mm) 1 3/4” (45 mm) Drive RR Drive LR Drive RF Drive LF Steer R Steer L Odometer Date Date16 None Odometer LD Steer6 3/8” R Steer (162 mm) LF Drive 2 1/4” RF (57 Drive mm) LR 1Drive 3/4” (45 RR mm) Drive Drive RR Drive LR Drive RF Drive LF Steer R Steer L Odometer Date mm) (45 3/4” 1 mm) (57 1/4” 2 mm) (162 Date 3/8” 166 None OdometerD LD Steer63/8” None R Steer (16216 mm) LF Drive 2 1/4” RF (57 Drive mm) LR 1Drive 3/4” (45 RR mm) Drive mm) (45 3/4” 1 mm) (57 1/4” 2 mm) (162 3/8” 6 D None 16 Date Odometer L Steer R Steer LF Drive RF Drive LR Drive RR Drive

16LS ‘L’ and Stroke Tag E 6 3/8” (162 mm) 2 1/2” (64 mm) 2” (51 mm) 1” 1/2” 1 3/4” 1 1/4” 1 1/2” 1 1/2” 1 miles 235,643 7/6 16LS7/6 ‘L’ and 235,643 Stroke miles Tag 1 E 1/2” 6 3/8” 1 1/2” (162 mm) 1 1/4” 2 1/2” 1 (64 3/4” mm) 1 1/2” 2” (51 mm) 1” 1” 1/2” 1 3/4” 1 1/4” 1 1/2” 1 1/2” 1 miles 235,643 7/6 mm) (51 2” mm) (64 1/2” 2 mm) (162 16LS7/6 3/8” 6 ‘L’ and 235,643 E Stroke miles TagTag 1 E 1/2”Stroke and 63/8” ‘L’ 1 1/2” (16216LS mm) 1 1/4” 2 1/2” 1 (64 3/4” mm) 1 1/2” 2” (51 mm) 1” mm) (51 2” mm) (64 1/2” 2 mm) (162 3/8” 6 E Tag Stroke and ‘L’ 16LS 7/6 235,643 miles 1 1/2” 1 1/2” 1 1/4” 1 3/4” 1 1/2” 1” 20 None D 6 25/32” (172 mm) 2 1/4” (57 mm) 1 3/4” (45 mm) 20 None D 6 25/32” (172 mm) 2 1/4” (57 mm) 1 3/4” (45 mm) mm) (45 3/4” 1 mm) (57 1/4” 2 mm) (172 25/32” 206 None D D 625/32” None (17220 mm) 2 1/4” (57 mm) 1 3/4” (45 mm) mm) (45 3/4” 1 mm) (57 1/4” 2 mm) (172 25/32” 6 D None 20 /62335mls112 /”114 /”214 1/4” 1 1/4” 2 3/4” 1 1/4” 1 3/4” 1 1/2” 1 miles 243,355 7/26 7/26 243,355 miles 1 1/2” 1 3/4” 1 1/4” 1 3/4” 2 1/4” 1 1/4” 1/4” 1 1/4” 2 3/4” 1 1/4” 1 3/4” 1 1/2” 1 miles 243,355 7/26 7/26 243,355 miles 1 1/2” 1 3/4” 1 1/4” 1 3/4” 2 1/4” 1 1/4” 7/26 243,355 miles 1 1/2” 1 3/4” 1 1/4” 1 3/4” 2 1/4” 1 1/4” 20LS ‘L’ and Stroke Tag E 6 25/32” (172 mm) 2 1/2” (64 mm) 2” (51 mm) 20LS ‘L’ and Stroke Tag E 6 25/32” (172 mm) 2 1/2” (64 mm) 2” (51 mm) mm) (51 2” mm) (64 1/2” 2 mm) (172 20LS 25/32” 6 ‘L’ and E Stroke TagTag EStroke and 625/32” ‘L’ (17220LS mm) 2 1/2” (64 mm) 2” (51 mm) mm) (51 2” mm) (64 1/2” 2 mm) (172 25/32” 6 E Tag Stroke and ‘L’ 20LS /82021mls112 ”112 /”234 1/4” 1 3/4” 2 3/4” 1 1/2” 1 2” 1/2” 1 miles 250,221 8/18 8/18 250,221 miles 1 1/2” 2” 1 1/2” 1 3/4” 2 3/4” 1 1/4” 1/4” 1 3/4” 2 3/4” 1 1/2” 1 2” 1/2” 1 miles 250,221 8/18 8/18 250,221 miles 1 1/2” 2” 1 1/2” 1 3/4” 2 3/4” 1 1/4” 8/18 250,221 miles 1 1/2” 2” 1 1/2” 1 3/4” 2 3/4” 1 1/4” Square Ports, Tag Square Ports, Tag Square Ports, Tag Tag Ports, Square Tag Ports, Square 20LS3 F 6 25/32” (172 mm) 3” (76 mm) 2 1/2” (64 mm) 20LS3 F 6 25/32” (172 mm) 3” (76 mm) 2 1/2” (64 mm) mm) (64 1/2” 2 mm) (76 3” mm) (172 20LS3 25/32” 6 F F 6 25/32” (17220LS3 mm) 3” (76 mm) 2 1/2” (64 mm) mm) (64 1/2” 2 mm) (76 3” mm) (172 25/32” 6 F 20LS3 and Marking and Marking and Marking Marking and Marking and 24 None D 7 7/32” (183 mm) 2 1/4” (57 mm) 1 3/4” (45 mm) 24 None D 7 7/32” (183 mm) 2 1/4” (57 mm) 1 3/4” (45 mm) mm) (45 3/4” 1 mm) (57 1/4” 2 mm) (183 7/32” 247 None D D 77/32” None (18324 mm) 2 1/4” (57 mm) 1 3/4” (45 mm) mm) (45 3/4” 1 mm) (57 1/4” 2 mm) (183 7/32” 7 D None 24 24L ‘L’ and Stroke Tag E 7 7/32” (183 mm) 2 1/2” (64 mm) 2” (51 mm) 24L ‘L’ and Stroke Tag E 7 7/32” (183 mm) 2 1/2” (64 mm) 2” (51 mm) mm) (51 2” mm) (64 1/2” 2 mm) (183 24L 7/32” 7 ‘L’ and E Stroke TagTag EStroke and 77/32” ‘L’ (18324L mm) 2 1/2” (64 mm) 2” (51 mm) mm) (51 2” mm) (64 1/2” 2 mm) (183 7/32” 7 E Tag Stroke and ‘L’ 24L Square Ports, Tag Square Ports, Tag Square Ports, Tag Tag Ports, Square Tag Ports, Square 24LS F 7 7/32” (183 mm) 3” (76 mm) 2 1/2” (64 mm) 24LS F 7 7/32” (183 mm) 3” (76 mm) 2 1/2” (64 mm) mm) (64 1/2” 2 mm) (76 3” mm) (183 24LS 7/32” 7 F F 7 7/32” (18324LS mm) 3” (76 mm) 2 1/2” (64 mm) mm) (64 1/2” 2 mm) (76 3” mm) (183 7/32” 7 F 24LS and Marking and Marking and Marking Marking and Marking and 30 None E 8 3/32” (205 mm) 2 1/2” (64 mm) 2” (51 mm) 30 None E 8 3/32” (205 mm) 2 1/2” (64 mm) 2” (51 mm) mm) (51 2” mm) (64 1/2” 2 mm) (205 3/32” 30 8 None E E 83/32” None (20530 mm) 2 1/2” (64 mm) 2” (51 mm) mm) (51 2” mm) (64 1/2” 2 mm) (205 3/32” 8 E None 30 DD (Bus DD (Bus DD (Bus DD (Bus DD (Bus 30 N/A 8 1/8” (206 mm) 2 3/4” (70 mm) 2 1/4” (57 mm) 30 N/A 8 1/8” (206 mm) 2 3/4” (70 mm) 2 1/4” (57 mm) mm) (57 1/4” 2 mm) (70 3/4” 2 mm) (206 1/8” 30 8 N/A N/A 8 1/8” (20630 mm) 2 3/4” (70 mm) 2 1/4” (57 mm) mm) (57 1/4” 2 mm) (70 3/4” 2 mm) (206 1/8” 8 N/A 30 Motorcoach) Motorcoach) Motorcoach) Motorcoach) Motorcoach) Square Ports, Tag Square Ports, Tag Square Ports, Tag Tag Ports, Square Tag Ports, Square 30LS F 8 3/32” (205 mm) 3” (76 mm) 2 1/2” (64 mm) 30LS F 8 3/32” (205 mm) 3” (76 mm) 2 1/2” (64 mm) mm) (64 1/2” 2 mm) (76 3” mm) (205 30LS 3/32” 8 F F 8 3/32” (20530LS mm) 3” (76 mm) 2 1/2” (64 mm) mm) (64 1/2” 2 mm) (76 3” mm) (205 3/32” 8 F 30LS and Marking and Marking and Marking Marking and Marking and 36 None 2.75” 9” (228 mm) 2 3/4” (70 mm) 2 1/4” (57 mm) 36 None 2.75” 9” (228 mm) 2 3/4” (70 mm) 2 1/4” (57 mm) mm) (57 1/4” 2 mm) (70 3/4” 2 mm) (228 36 9” None 2.75” 2.75” 9” None (228 mm)36 2 3/4” (70 mm) 2 1/4” (57 mm) mm) (57 1/4” 2 mm) (70 3/4” 2 mm) (228 9” 2.75” None 36

NOTES: NOTES: NOTES: NOTES: NOTES: (1) Manufacturer’s rated stroke, which is sometimes marked on chambers, (1) Manufacturer’s rated stroke, which is sometimes marked on chambers, chambers, on marked sometimes is (1) which Manufacturer’s stroke, rated rated stroke, which Manufacturer’s is(1) sometimes marked on chambers, chambers, on marked sometimes is which stroke, rated Manufacturer’s (1) should never be used as the adjustment limit. Brakes should be adjusted so should never be used as the adjustment limit. Brakes should be adjusted so so adjusted be should Brakes limit. should adjustment the never as be used usedbe as thenever adjustmentshould limit. Brakes should be adjusted so so adjusted be should Brakes limit. adjustment the as used be never should pushrod travel does not exceed the respective stroke limit in the regulation. pushrod travel does not exceed the respective stroke limit in the regulation. regulation. the in limit stroke respective the pushrod exceed travel not does does not travel exceed thepushrod respective stroke limit in the regulation. regulation. the in limit stroke respective the exceed not does travel pushrod (2) A with new linings that have not yet fully seated to the drum (2) A drum brake with new linings that have not yet fully seated to the drum drum the to seated fully yet not have that (2) A drum linings brake new with with new brake linings drum that A have(2) not yet fully seated to the drum drum the to seated fully yet not have that linings new with brake drum A (2) has the potential to exceed the stroke limit in the regulation upon a full has the potential to exceed the stroke limit in the regulation upon a full full a upon regulation the in limit stroke the has the potential exceed to to exceed potential the strokehas limit in the regulation upon a full full a upon regulation the in limit stroke the exceed to potential the has brake application of 90 to 100 psi (620 to 690 kPa). Drum brakes with new brake application of 90 to 100 psi (620 to 690 kPa). Drum brakes with new new with brakes Drum kPa). 690 to (620 psi brake100 to application90 of of 90 to 100 application psi (620brake to 690 kPa). Drum brakes with new new with brakes Drum kPa). 690 to (620 psi 100 to 90 of application brake linings should be checked regularly. linings should be checked regularly. liningsregularly. should checked bebe checked should regularly.linings regularly. checked be should linings (3) SAE J2899 is a new alphanumeric marking option first implemented on (3) SAE J2899 is a new alphanumeric marking option first implemented on on implemented first option marking (3) SAE J2899 alphanumeric is a new new a is alphanumeric J2899 SAE marking(3) option first implemented on on implemented first option marking alphanumeric new a is J2899 SAE (3) some products in 2018. some products in 2018. some products 2018. in in 2018. products some 2018. in products some © Commercial Vehicle Safety Alliance All rights reserved. © Commercial Vehicle Safety Alliance All rightsreserved. reserved.rights All Alliance Safety Vehicle Commercial © reserved. rights All Alliance Safety Vehicle Commercial © © Commercial Vehicle Safety Alliance All rights reserved. Air Brake Pushrod Stroke

The brake system on a commercial motor vehicle must work well every What is a brake chamber pushrod stroke violation? Figure 1 What to do when the brake chamber stroke violates Pushrod stroke = B - A time, under all conditions. If not, the driver’s life and the lives of others A brake violation occurs when the brake chamber pushrod stroke A the regulations are at risk. exceeds the stroke limits set by regulations. B When brake chamber pushrod stroke exceeds the regulatory stroke limit, what you do about it depends on whether your vehicle is To stop effectively in every braking situation, all components in the Keeping a brake chamber pushrod within regulatory stroke limits equipped with manual or self-adjusting brake adjusters. air brake system, including the foundation brakes, must be properly ensures there is sufficient pushrod travel to apply full force to the installed, adjusted and maintained by qualified technicians. Stroke foundation brake under all operating conditions. The limits are based • Self-adjusting brake adjusters – SABAs should not be manually limits specified by Canadian and U.S. regulations help maintenance on the size of the brake chamber and whether the chamber is a standard adjusted; they will do so automatically. If a chamber with a SABA Mark pushrod has excessive stroke, there is a problem with the foundation brake, technicians and enforcement personnel inspect and identify brakes that or long-stroke design. See Table 1. here and measure may not be properly adjusting. how far it travels Pushrod stroke the drum, the SABA itself or other components. The entire wheel with brakes applied end (chamber, SABA, drum, hub and other hardware) should be Pushrod stroke that exceeds regulatory limits not only violates federal, (see image at right) During day-to-day driving, a driver cannot tell how well the brakes will state, provincial or territorial regulations but, more importantly, results Brake pedal released Brake pedal fully applied inspected and serviced by an authorized brake technician as soon work during an extreme braking maneuver. The most effective way in a decline in the braking force – eventually to zero – provided by the at 90-100 psi (620-690 kPa) as possible. A manual readjustment may temporarily improve to confirm that S-cam drum brakes are within regulatory limits is to foundation brake, which will increase the distance it takes to stop the the stroke length, but it can cause damage and does not fix the measure pushrod stroke. Pushrod stroke is the length in inches or vehicle. underlying problem. The stroke violation may return within a few millimeters that the pushrod travels when the brake is fully applied. If brake applications and, most importantly, stopping ability may be Note: It is normal for pressure to drop slightly as brakes are applied. the pushrod stroke is beyond the limit in the regulation, the foundation manufactured in the US after Oct. 20, 1994, or in Canada significantly impaired. If multiple brake applications cause the pressure to drop below 90 psi brake may no longer be able to provide full braking force and the brake after May 31, 1996, must be equipped with self-adjusting brake • Manual brake adjusters – Manual brake adjusters, permitted on (620 kPa), pause the procedure to rebuild reservoir pressure to 90 to may need servicing. adjusters (SABAs) to automatically account for normal brake system older vehicles, must be readjusted by a qualified individual on a 100 psi (620 to 690 kPa), then resume with the engine off. wear. Manual brake adjusters are only permitted on legacy vehicles regular basis. If regulations require the vehicle to be equipped Brake system violations represent the most common reason commercial manufactured prior to the dates above and must be regularly adjusted with SABAs based on its date of manufacture, installing and using motor vehicles are placed out of service during roadside inspections. by hand. Step Four – Compare your recorded pushrod stroke values with the a manual brake adjuster in place of the self-adjusting one is a When pushrod stroke exceeds the regulatory limit, a violation exists and stroke limits in the regulation for your brake chambers. See Table 1. If violation. something may be wrong in the foundation brake system or with the The use of SABAs has helped to significantly reduce the rate of out- any chamber stroke measurement is near, at or beyond the prescribed slack adjuster. of-service brake violations. However, even with properly working regulatory stroke limit for your chamber type or size, the foundation SABAs, abnormal or excessive wear or broken components can result brake, brake chamber, SABA, drum and wheel-end need to be inspected Notes about self-adjusting brake adjusters By following manufacturers’ recommended foundation brake in excessive pushrod stroke and must be properly serviced. in more detail and serviced as soon as possible. If any pushrod stroke When SABAs exceed the regulation limit, consider the following maintenance intervals (for lubrication, lining replacement, wear measurement exceeds the prescribed stroke limit, a violation exists. Any before adjusting the brakes: tolerances, etc.), regularly measuring the pushrod stroke and proactively How to correctly measure the brake chamber stroke vehicle or combination of vehicles with 20 percent or more of the wheel • Drivers may be legally prohibited from adjusting SABAs in some addressing issues immediately, crash risk can be mitigated, safety To measure chamber pushrod stroke, you will need a ruler, chalk, ends containing brake violations is out of service per the CVSA North jurisdictions. ratings may improve, and the chances of a violation or out-of-service flashlight, eye protection, pencil and paper. You will also need another American Standard Out-of-Service Criteria. • The motor carrier may prohibit the driver from adjusting SABAs. order can be reduced. person to apply the service brakes. The procedure is as follows: • Do not readjust a SABA unless you have been specially trained to What about free-stroke and slack? do so. Step One – Ensure the vehicle is in a safe location and make sure the Measuring chamber free-stroke or chamber pushrod slack, which is • Manually adjusting a SABA improperly can damage it. The wheels are properly chocked to prevent rolling. Release the spring the distance you can pull the brake chamber pushrod by hand using manufacturer’s instructions must be precisely followed. brakes. Confirm your dash gauge indicates 90 to 100 psi (620 to 690 a bar or lever without applying air pressure to the chamber, does not The brake chamber will return to the excessive stroke condition kPa) supply pressure in the air brake system reservoirs. Then, shut confirm a brake is working properly under all conditions. Chamber • until the cause of the problem is repaired. Excessive stroke can off the engine. Note: Supply reservoir pressure exceeding 110 psi free-stroke longer than 3/8” to 3/4” (10 to 20 mm) may indicate a return quickly, in just a few brake applications. (758 kPa) will result in incorrect pushrod stroke assessments. more serious issue. But shorter free-stroke does not confirm proper brake chamber stroke. • If the driver readjusts the brake chamber stroke, he or she must Step Two – Visit each brake and confirm it is in the normal released continue to monitor the brake chamber stroke and report any position with nothing wrong or out of place. Mark each pushrod to How can brake chamber stroke indicators help you? excessive stroke problems to the motor carrier or service provider. establish a reference starting location. This should be level with Checking the stroke typically means getting under the vehicle to take • Be sure that any technician hired to correct an excessive brake where the pushrod exits the brake chamber or the chamber mounting measurements before and during a brake application. Brake chamber chamber stroke is qualified and will fix the underlying cause. bracket. Note where the pushrod mark started out and where it ends stroke indicators can be installed to help identify when the stroke • If a brake chamber with SABAs exhibits excessive stroke, some up, then measure the difference in the next step. See Figure 1. reaches or exceeds regulatory limits. Stroke indicators can provide a of the contributing causes could include worn or seized clevis pin visual aid to make stroke assessment easier, possibly without the need connections, worn S-cam bushings, cracked chamber bracket or Step Three – Have the other person press and hold the service to go under the vehicle. It is recommended, however, that the previously cam tube welds, worn rollers, cracked drums, worn linings, worn brakes (pushing the brake pedal all the way down until it stops) while mentioned four-step procedure be completed on a regular schedule. drums and/or loose mounting hardware. A trained brake technician you measure and record the distance each pushrod mark moved (or should diagnose and correct the underlying problem(s). “stroked”).