BENDIX TCH-001-045 User's Manual
Contents
1. below the drain level During operation the piston rods dip into the trapped oil and carry the oil to the cylinder walls The increased amount of oil on the cylinder walls results in more oil migrating past the piston rings TF 750 compressors are more susceptible to this condition because they have longer strokes If the vehicle is equipped with a TF 750 compressor and thus far the cause for excessive oil passing has not been found install a bottom drain cover If either the engine power angle or tilt is excessive add a bottom drain to the compressor and place vehicle back into service Check the engine crankcase pressure with a test gauge and compare the reading to engine specifications Excessive engine crankcase pressure can cause oil to be forced pass the piston rings increasing oil passing If excessive pressure is found repair the cause of the excessive pressure and place vehicle back into service If engine power angle and tilt are not causing flooding or the compressor is already bottom drained and engine crankcase pressure is within specifications proceed to Step 8 Step 8 Compressor Replacement Replace the compressor only after reviewing all items in each of the preceding steps TABLE A COMPRESSOR amp AIR DRYER APPLICATION SELECTION MATRIX This matrix is intended for use as a general guide if you have experience with applications contrary to those listed below Use your experience as a guide If your vehicle is equipped with high ai2. through the system and into the reservoir If after reviewing these general comments excessive oil passing is still suspected proceed to Step 1 Step 1 Reservoir Draining If excessive oil is passing from the air compressor the air dryer filter element and desiccant may become saturated One of the first signs of oil saturated filter element or desiccant cartridge is moisture appearing in the reservoirs The first step in determining if a compressor is passing an excessive amount of oil is to drain the reservoirs and monitor the amount of water and or oil removed Check reservoir drain valves to ensure that they are functioning properly It is recommended that the vehicle should be equipped with functioning automatic valves or have all reservoirs drained to zero 0 psi 0 kPa daily or optimally to be equipped with a desiccant type air dryer prior to the reservoir system If when draining the reservoirs there is an absence of water and or oil the compressor and all compressor support systems are operating properly and there is no need to proceed further If the expulsion from the dryer purge occurs in a location such that it affects vehicle appearance reroute the purge If water and or oil are present and the duration since the last reservoir draining is known and consistent with Table A go to Step 2 If the reservoirs have not been drained according to Table A follow the suggested frequency for two cycles If at the end of the second
3. Technical Bulletin Bulletin No TCH 001 045 A Effective Date 5 1 98 Cancels PRO 01 32 dated 8 1 88 Page 1 of 6 Subject Troubleshooting Compressor Oil Passing General Comments Some oil carryover from the air compressor into the air brake system occurs as a normal part of all air compressor operation Compressors require oil carry over to lubricate the compressor s valves and rings It is typical to find some presence of oil at the inlet and discharge ports of the air compressor Oil present at the exhaust of drain valves air dryers or aftercoolers is normal and indicates that these components are functioning properly removing contaminants from the system Vehicles equipped with a desiccant type air dryer that incorporates a filter separator for removing oil from the air will normally minimize oil passed through to the reservoir The oil collects in the air dryer with condensed moisture and is periodically purged Often the routing or location of the air dryer exhaust port can amplify concerns about oil passing depending on where the purged oil water mixture is expelled on the vehicle e g on a fender or onto a fuel tank This can mistakenly be identified as problem oil passing when in actuality the air dryer and compressor are functioning properly Vehicles may be equipped with condensing type aftercoolers or drain valves instead of an air dryer These devices have little or no affect on preventing oil or water from being passed
4. cycle water and or oil are drained further investigation is needed Proceed to Step 2 K An absence of water and or oil after the second draining indicates the compressor and all compressor support systems are operating properly Continue to perform reservoir draining on a regular basis as outlined in Table A Step 2 External Influences At this point it should have been established through observations made in Step that conditions exist causing excessive oil passing This does not indicate that immediate removal of the compressor is necessary or that the compressor is the root cause for this issue Removal of the compressor at this point usually leads to the replacement of several compressors over a period of time without resolution of the issue The support systems which control and contribute to the compressor operation must be examined There are many external influences which can affect compressor oil passing The influences can be grouped into subcategorizes as follows Vehicle operation Engine operation Compressor inlet air supply system Compressor coolant supply system Compressor oil supply and return system Proceed to Step 3 Step 3 Vehicle Operation Vehicle operation is the driving factor for compressor performance and influences all of the systems that control and contribute to compressor operation Check vehicle system leakage Vehicle system leakage should not exceed industry standards of 1 psi 6 9 kPa pr
5. e inlet of the compressor What is the maximum coolant temperature at the outlet port of the compressor Is oil pressure within engine specifications Is engine crankcase pressure within engine specifications
6. essure drop per minute without brakes applied and 3 psi 20 7 kPa pressure drop per minute with brakes applied If leakage is excessive check for system leaks and repair After determining that the system leakage meets industry standards the compressor duty cycle must be established Duty cycle is the percent of time the compressor is loaded during a period of operation As duty cycle increases the amount of oil passed into the system increases Example If two compressors which pass the same amount of oil when operated at the same duty cycle are placed on two vehicles which are identical except for duty cycle the compressor on the vehicle with the greater duty cycle would pass more oil into the system The amount of effluent purged from the dryer would be greater on the vehicle with the greater duty cycle Thus the relative amount of oil at the purge of the dryer is not only an indication of the level of oil passed by the compressor but also the duty cycle of the compressor Compressors that operate with duty cycles of 25 or less will have an expected life equal to the normal warranty period As duty cycles extend beyond 25 the expected life will decrease It is recommended that the compressor duty cycle should not exceed 25 and the average charge period should not exceed 90 seconds to ensure the normal life of the compressor and dryer By keeping the charge time at or below 90 seconds the compressor operating temperature is lower reducing oi
7. l consumption carbon formation and discharge temperatures By keeping discharge temperatures lower the dryer s ability to remove oil and moisture is increased Once the duty cycle is established review Table A for the vehicle application and make sure that the compressor and air dryer combination installed on the vehicle match those recommended based on duty cycle If the vehicle is not properly equipped a change of the compressor and or air dryer maybe necessary If the duty cycle exceeds the recommended 25 two options are available e Reduce the amount of demand by redesigning the air system e Increase system maintenance through more frequent reservoir draining dryer cartridge change out and discharge line replacement Optimizing systems in Steps 4 5 6 and 7 may also help if the duty cycle cannot be reduced If the duty cycle does not exceed 25 proceed to step 4 Step 4 Compressor Inlet Air Supply System Check for damaged defective or dirty air filter on engine or compressor Check for leaking damaged or defective compressor air intake components i e induction line fittings gaskets filter bodies etc Damaged or leaking lines as well as dirty filters result in unfiltered intake air being supplied to the compressor Operating the compressor with unfiltered intake air results in excessive wear to the upper piston rings and cylinder bores in a relatively short time If any one of these conditions is found make all necessa
8. n of the compressor cylinders or cylinder head If any one of the above indicators is present measure coolant temperature under normal operating conditions If coolant temperature is above recommendations inspect the coolant lines and fittings for accumulated rust scale kinks and restrictions Remove accumulated grease grime or dirt from the cooling fins Optimum cooling is achieved when engine coolant flows into the compressor at one end and out at the opposite end with the inlet at the lowest port recommended coolant flow is 0 5 gpm at idle and a minimum of 2 5 gpm at max rpm If these actions do not succeed in reducing the coolant temperature consult the engine manufacturer for determination of additional methods to reduce the coolant temperature If the compressor operated under these conditions replace the compressor If coolant temperature is at or below recommendations proceed to Step 6 Step 6 Compressor Oil Supply and Return System Check the engine oil pressure with a test gauge and compare the reading to the engine specifications Higher than specified pressure can result in an excessive amount of oil in the compressor crankcase which will increase the likelihood of oil on the cylinder walls and opportunity to migrate past the piston rings Bendix does not recommend restricting the compressor oil supply line because of the possibility of plugging the restriction with oil contaminants If the oil pressure is high make necessary re
9. pairs to return the oil pressure to engine specification and proceed to the next paragraph Oil return to the engine should not be in any way restricted Restrictions present in the oil drain connection from the compressor to the engine can cause a build up of oil in the compressor crankcase sump and increased oil passing There is no easy method to measure the quantity of oil drain back or to monitor crankcase oil level By design the amount of drain back to the engine should be sufficient under most circumstances Areas to check to make sure the oil drain is as efficient as possible are e For flange mounted compressors internally drained back to the engine it is important that the drain ports are aligned and not restricted by gasket or sealant used during the compressor installation e For compressors with external drain lines check for excessive bends kinks and restrictions in the oil return line Minimum recommended oil return line size is 1 2 I D 12 7mm Return line must constantly descend from the compressor to the engine crankcase If restrictions in the drain back system are found make appropriate repairs If oil pressure and oil return are found to be OK or repairs were made proceed to Step 7 Step 7 Engine Operation Engine power angle and tilt can affect oil drain back from the compressor on flange mounted applications These angles cause the drain to be higher than a portion of the crankcase resulting in the trapping of oil
10. r usage accessories not referred to below use the compressor duty cycle guide at the bottom of the matrix i e air wipers tag axles regularly lifted for cornering large accessory air cylinders air start etc Application Braked Comp Axles Type SchoolBus 23 SSO V v Highway Travel Coach 23 TF SSO_ Vo vV D City Transit Bus 23 rezso fJ Jy y Pick up amp Delivery 23 Tesso V vV T f ES E ee se Line Ha d 2s sso vV y T T s ro v a a ee ee Rural or Commercial Refuse 2 3 TF 750_ J V f Residential Refuse 23 TF 750_ fJ YT City Refuse with Work Brake 2 3 TF 750_ s D Concrete Mixer 24 me7so fJ v l Ni Dump Truck ae E S E a E Off Highway Construction 27 Tr1400 vx BES a ee e E E E ee eee E eee ee Logger SS rg ff vy ff wa o o 4 CTI Al Rl 20 60 Compressor Duty Cycle Low Low High High High Reservoir Drainage Check Monthly Every Month or 4000 miles Frequency In Off Highway applications where electronic engines are used a TF 550 compressor may be sufficient Required to run two 2 governors one at 85 psi and one at 120 psi to reduce strain on drive train when compressor inlet is turbocharged Vehicles without an air dryer must be drained daily Note It is recommended that the compressor duty cycle not exceed 25 to ensure the normal life of the compre
11. ry repairs and or filter replacement Once the compressor is damaged in such a manner the compressor must be replaced The maximum allowable air inlet restriction vacuum is 25 inches 6 2kPa of water Exceeding this limit will cause air along with oil to be drawn from the compressor crankcase into the delivery air If high inlet vacuum exists check compressor air inlet line for kinks excessive bends or other restrictions The compressor intake should not be connected to any part of the exhaust gas recirculation E G R system on the engine Reconfigure the inlet to remove this connection if present Perform necessary repair or replacement to damaged or malfunctioning components and place vehicle back into service If inlet air is clean and free of restriction proceed to Step 5 Step 5 Compressor Coolant Supply System Coolant temperature at the water outlet port of the compressor must not exceed 220 F 104 C Temperatures beyond this level result in high cylinder temperatures The results of high temperatures are Cylinder bore distortion causing oil to pass by the rings Breakdown of lubrication between piston ring and bore causing premature wear Breakdown of oil causing carbon formation High dryer inlet temperatures causing a loss of drying efficiency Indicators of insufficient cooling include e Heavy carbon deposits in the cylinder head discharge line or fittings e Carbonized oil deposits in the inlet cavity e Discoloratio
12. ssor In circumstances where duty cycle is anticipated to exceed 25 a larger compressor model i e a TF 750 instead of a TF 550 is recommended INFORMATION SHEET If further technical assistance is required fill out the following information prior to contact General Information Company Name Contact Name Title Phone Number Fax Number Vehicle Information Year Make Model Mileage Hours Unit Number Number of braked axles Vocation Location Configuration 4x2 4x4 Number of similar units in fleet Engine Information Manufacturer Model HP rating Maximum speed Mileage Hours Compressor Information Model Pc No Serial No Mileage Hours Inlet configuration Naturally Aspirated Turbocharged Air Dryer Information Model Pc No Serial No Time in service time since last cartridge change Location on vehicle Discharge line length Performance Information What is the reservoir draining interval What is the quantity of oil water present when drained What was the system pressure drop after 5 minutes without brakes applied What was the system pressure drop after 5 minutes with brakes applied What is the compressor duty cycle What is the average charge time What is the average purge time What is the air cleaner service interval What is the maximum vacuum reading at th
Download Pdf Manuals
Related Search