3Description Parallelogram design sliding tandem air suspension. Upper & lower control arms are parallel to each other.Single unified frame bracketThe air springs mount directly over the axles.
4How Is It Different From A Trailing Arm Suspension? Meritor Highway ParallelogramA Tandem Suspension SystemTwo Separate Suspensions on a FrameTwo Frame BracketsSingle Unified BracketExtremely Lightweight SystemAir Springs Mounted Directly Over The Axles
5How Does It Work? Trailing Arm Suspension Meritor Parallelogram Upper & lower Control arms parallel…Air springs over the axles = 100% air rideA smooth ride for the driver and cargoNo fore/aft movement that trailing Arm suspensions haveNo roll torqueTrailing Arm MovementRoll Torque on Axle
6Torque Tube StablRide™ 7/16” thick Torque Tube links the Upper Control Arms together on each axle.Controls Lateral Roll to a Maximum of 2 Degrees.No twisting on the axlesStablRide™
7What Is Dock Walk ?Walking Away from the Dock During Forklift Loading & Unloading .
8What Causes Dock Walk? Trailing Arm Suspension Can… Have Horizontal MovementHeavy Add-On Devices To Prevent Dock Walk
9How Does The RHP-11 Stop Dock Walk? Suspension Geometry Eliminates Dock Walk without Add-On Devices...No Dock Walk with Vertical MovementNo Forward Movement...Landing Gear will not Fold
10IdentificationThe identification tag is located on the left (roadside) of the suspension near the pin release handle.The Model number on the tag provides suspension and axle bill of material information.AND RIDE HEIGHT
12RHP, producedthru 2007MPA Ride Sentry2007, 2008 = current
13Inspection Before each trip. Visually inspect the suspension and listen for air leaks.After 1000 miles and MINIMUM annually thereafter. (inspect at each service visit / wheel end.)Visually inspect all bolts for looseness or movement. See Figure 3.1 on page 5 of Maintenance 14STighten loose fasteners to the correct torque as per torque chart on page 24 of Maintenance 14S.
16Inspection - Continued Check for looseness of the alignment pivot bolts.Check for looseness of the lower control arm clamp bolts and pivot bolts.If the bolts are loose realign the axles prior to retightening the bolts.Replace damaged fasteners to maintain the correct torque and specifications and to comply with warranty requirements.Torque chart is on page 23 of MM-14S
17Inspection - Slider Inspect for loose, broken or missing fasteners. Inspect the slider locking pins, slider pull-bar mechanism and slider wear pads for signs of excessive wear or binding.Inspect the front &rear hold down clips to insure that they are secured correctly around the body rails. Damage to the front clip is evidence of high speed repositioning and the slider should be inspected for damage.Inspect the slider box and cross members for damage.
18Inspection – Air suspension Inspect the following areas: Control arms & brackets.Inspect bushings for wear.Axles and axle seatsCross tubes and frame.Shock absorber
19Upper Control Arm Inspection Park the trailer on a level surface. Chock the wheels to prevent moving. Support the trailer with safety stands.Use a flashlight to inspect all eight upper control arm bushings to determine if any of the upper controls have shifted to one side.
20Upper Control Arm Bushing Inspection Condition 1 Condition 1 - NormalBushing flanges appear intact on both sides of the tubeEverything is centered within the frame bracket or axle seat.SEE SEPARATE BUSHING PP
28Shock Absorber Inspection Inspect Shocks…Replace Shocks with Damaged Bushings
29Shock Absorber Inspection Inspect Shocks…Replace Shocks That are Bent or Damaged
30Shock Absorber Inspection Replace Shocks That Have Broken Dust Tubes
31Height Control Valve (HCV) There are four HCV configurations:No DumpAuto DumpManual Dump / Manual ResetManual Dump / Auto ResetNo Dump ( Standard )Trailer will maintain ride height as long as the trailer is connected to an air supply.
33Height Control Valve (HCV) - continued Manual dump / manual reset.The driver can dump and fill the air springs by using a manual control valve.Manual dump / Auto reset.The driver dumps the air spring by using a manual control valve.Air springs are filled when the trailer brakes are released.Auto DumpDumps the air from the air spring and lowers the suspension when the trailer brakes are engaged.Fills the air spring when the trailer brakes are released
34HCV Operational Test (unloaded trailer) Park trailer on level surface and chock wheelsDisconnect the height control linkage.Check air supply to valve. A minimum of 65 p.s.i. is required for the test.Rotate lever up degrees. In two to six seconds.Rotate the lever to the neutral position air. Airflow should stop.Repeat test in down position.If air does not flow to and from the springs. Used compressed air to clean the screens in the delivery and exhaust port.If air still does not flow after cleaning the ports, replace the HCV.
35Ride Height Measurement Refer to manufacturers specifications for correct ride height. (Where do we find information?)Ride height is measured from the axle centerline to the bottom of the slider frame.Unload the trailer before adjusting ride height.Support the trailer king pin at the normal operating height.If the ride height does not meet the trailer manufacturers specifications adjust the ride height.
36Ride Height Adjustment Disconnect the height control valve linkage from the lever arm.Deflate the air springs by lowering the lever arm 30 – 45 degrees.Inflate air springs to the correct ride height by holding the lever arm in the up position .Insert the locating pin or 1/8” drill bit at the lever arm.Loosen the ¼” adjusting screw on the lever and allow the lever arm to swing free,Align the lever arm to the opening in the linkage and loosely install the bolt.Tighten the ¼” screw and remove the pin.Tighten the linkage bolt and re-check ride height.
38Axle Alignments – Front axle first followed by Rear Axle Align Front axle to king pin A BAlign Rear axle to front axle C D.To obtain the correct alignment the difference between A&B not to exceed 1/8” C&D must not exceed 1/16”.
39Adjust Alignment – Front Axle WITH SUSPENSION RELAXED.Loosen the bolt that connects the upper control arm to the frame bracket.You must loosen this connection before you align the axle to prevent premature bushing and component damage.Loosen the clamp bolts and adjust the length of the lower control arm so that the differences between KP A&B does not exceed 1/8”.When the axle is aligned tighten the lower control arm clamp bolts to 160 – 170 lb-ft.Tighten the upper control arm pivot bolt to lb-ft.
40Adjust Alignment – Rear Axle Loosen the bolt that connects the upper control arm to the frame bracket.You must loosen this connection before you align the axle to prevent premature bushing and component damage.Loosens the clamp bolts on the lower control arm and adjust the length of the lower control arm so that the differences between C&D does not exceed 1/16”.When the axle is aligned tighten the lower control arm clamp bolts to 160 – 170 lb-ft.Tighten the upper control arm pivot bolt to lb-ft.
42Chronology of Bushing Improvements Original Green Urethane Bushing; No Corrosion Protection on Inner MetalBlack Bushing with Microtect Coating on Inner Metal19981999200020012002200320041997Black Urethane Bushing with Zinc Dichromate Coating on Inner MetalBonded Rubber Bushing
43Two-Piece Urethane Bushing Operational Characteristics Rotation can occur between UCA and bushing as well as bushing and inner metal. Sliding friction is always present.Urethane Bushing Free to rotateInner Metal Fixed/Clamped
44Bonded Rubber Bushing Operational Characteristics Rotation occurs only through the deflection of the rubber. No sliding friction between bushing and either UCA or inner metal.Rubber Bonded to Inner MetalRubber OD Interference/Press fitInner Metal Fixed/Clamped
45Upper Control Arm Bushing Installation Tool Bonded Bushings must be installed with an installation tool.The ArvinMeritor parts number for the tool is A-3256-H-1152The tool consists of:1 Draw bolt1 Draw nut1 Draw plate2 Flat washers
46Upper Control Arm Bushing Installation 1 Using P-80 lubricant or a non-petroleum based liquid soap lightly lubricate the inside diameter of the upper control arm bushing tubes.Using P-80 lubricant or a non-petroleum based liquid soap lightly lubricate the outer diameter of the bonded bushing.THESES STEPS MUST BE FOLLOWED TO ASSURE PROPER BUSHING INSTALLATION!!!
47Upper Control Arm Bushing Installation 2 Place the draw plate on the outside surface of the upper control arm tube.Insert the draw bolt with a flat washer through the draw plate and bushing tube.place the bushing over the draw bolt and into the upper control arm bushing tube.Thread the draw nut and washer onto the draw bolt until it sets against the bushing.Snug the draw bolt while ensuring that the bonded bushing and draw bolt rest securely against the bushing.
48Upper Control Arm Bushing Installation 3 While holding the draw nut with a wrench, turn the draw bolt CLOCKWISE using a impact wrench no greater than ½” drive at a reduced steady speed.Draw the bonded bushing into the upper control arm bushing tube.if the bolt stops turning or extreme resistance is present:reverse the impact wrench and loosen the tool assembly.Inspect all components for damageReset the draw plate ensuring that the bonded bushing is seated against the bushing tube.Verify lubrication on the bushing and tube and repeat the procedure.
49Upper Control Arm Bushing Installation 4 Continue rotating the draw bolt until the bolt stops turning and the bushing is fully inserted.OVERTIGHTENING CAN DAMAGE THE DRAW BOLT OR NUT.Ensure that the bonded bushing is centered in the upper control arm bushing tube from side to side.Install the thrust washers onto the bonded bushings.
50Upper Control Arm Bushing Installation 5 Release the pressure on the porta-power This will allow the upper control arm to be positioned into the frame brackets by hand.Position the upper control arm into the frame brackets.Ensure that the thrust washers remained in position on the bonded bushing.Using the recorded pivot bolt orientation, insert a new pivot bolt, flat washers and nut on the road side.Repeat for the curb side.Loosely install the roadside and curbside nuts. DO NOT TIGHTEN AT THIS TIME !
51Upper Control Arm Bushing Installation 6 Repeat the procedures shown for the upper control bushings at the frame bracket for the upper control arm bushings at the upper axle seats.Loosely install the road side and curbside nuts and bolts as in the steps followed for the frame bracket bonded bushing installation.
52Upper Control Arm Bushing Installation 7 Using a floor jack bring the axle to correct ride height. Refer to the trailer manufacturers specifications.Apply the required torque to all pivot bolts except the alignment positions.Align the axles and torque the alignment bolts.Reinstall the wheels and tires.Remove the safety stands and slowly lower the trailer back down onto the suspension.Apply air to the suspension system and check the ride height to verify that it is correct.
53Lower Control Arms Bushing Replacement 1 Lift the trailer off the ground with the landing legs lowered.Raise the trailer so that the tires are off the ground.Support the trailer with safety stands under the frame.Set the parking brake.Exhaust the air pressure from the air springsRemove the wheels from the axle you are removing the bushings to access the pivot points.
54Lower Control Arms Bushing Replacement 2 If there is corrosion between the pivot bolts and the inner sleeve use an impact wrench to spin the bolt heads at all four connections to disengage the bolts from the corrosion to the inner sleeve.If the nut is tamper-proof remove the nut by grinding off the tack weld between the nut and bolt thread.Use a pipe wrench to grip the nut while using an impact wrench on the bolt head.Remove the pivot bolts. Remove the lower control armRemove the bushings and inner sleeves.Remove any burrs and clean the ID of the lower control arm.Insert new bushings and sleeves into the lower control arm. Use a liquid soap for lubrication.Position the lower control arm into the frame bracket and lower axle seat.Install new bolts washers and nuts.Torque the nuts to lb-ft.
55Frame Bracket Side Plate Repair Procedures TP0571BINDER
56New Repair procedure – RHP/MPA In addition to frame bracket… New Repair procedure – RHP/MPA In addition to frame bracket….axle seat repairsTP0897 – RHP/MPA Axle Seat RepairAxle seat inner metal wear is now repairable. Axles seats do not need to be replacedThis repair procedure will not correct wear from UCA.If the thickness of the material is less than inch: Replace the axle seat..
57New Repair procedure FOR AXLE SEAT – RHP/MPA Axle seat inner metal is cut out with a torch or similar toolA repair slug is installed with use of tool. This tool will set the slugs to the correct dimension for proper bushing clamp.