0586079 JOHNSON ARMATURE ASSY.

OPERATION, MAINTENANCE AND SERVICE MANUALS -TIB OF MAY 13.92 -CC 3101- REDUCED RIMPULL & PT OVERHEATINGTIB OF JULY 9.92 -CC 1300- NEW CAT OIL RECOMMENDATIONSTIB OF JULY 9.92 -CC 3101- VCTC CONTROL LINKAGE ADJUSTMENTTIB OF AUGUST 27.92 - CC 3101 - USING THE VCTC CORRECTLY.DISTRIBUTION:TECHNICAL COMMUNICATORSSERVICE / SALES MANAGERSSERVICE / SALESMENTRAINING DEPARTMENTS / OPERATOR TRAINERSCUSTOMERSProblem:
Misunderstanding the VCTC feature by the loader operators, can lead to higher fuel consumption, shorter tyre and VCTC clutch life, VCTC/TRSM oil overheating and lack of implement hydraulic speed for efficient loading.I.E. HIGHER THAN NORMAL OWNING AND OPERATING COSTS - or - HIGHER COSTS PER TON loaded.The name of the game is simple. The more H-Power is absorbed by the Power Train, the less HP/Speed is available for the implement hydraulics and visa versa. - In addition, the higher the torque through the Power Train, the shorter it's components life.DISCUSSION:The 988B was rated 375 HP at 2200 RPM. - Stalling the VCTC in the Maximum Rimpull position, usually loaded the Engine to around the FLRPM (Full Load RPM) - which is a relatively "soft" or "matched" Torque Converter. - For certain applications, this amount of Rimpull was not good enough - hence a "High Rimpull" CMP version was available. (Block Handling etc). - (The correct procedure how to run a VCTC stall test can be round in the Service Manual) The 988F is rated 400 HP at 2000 RPM. - Stalling the VCTC in the Maximum Rimpull position will put the Engine into "Deep Lug" at around 1850 RPM. - The CAPACITY of this Torque Converter is called "stiff" or "overmatched". - Hence - the former "High Rimpull" version is built into the Standard Machine, WHEN THE VCTC IS SET TO THE MAX RIMPULL POSITION.The HP consumption for this setting can be relatively high.Solution:
FOR NORMAL LOADING APPLICATIONS, the maximum VCTC Rimpull setting will almost certainly mean TOO MUCH Rimpull, Tyre slippage, excessive Tyre wear, engine HP wastage, slower implement hydraulics and steering response. - A VCTC control lever setting resulting in a stall speed of somewhere around 2000 RPM, would be more "normal" for a classic loading application. - Naturally, an ideal setting can be either higher or lower than that.TEACH the Operators now to select the correct Rimpull according to underfoot conditions to OPTIMIZE Rimpull, Tyre life, Penetration, Production etc. When Tyre slippage is visible, traction has already been lost & therefore the penetration force is reduced! SPINNING TYRES EQUALS POWER IS ONLY PERCEPTION NOT FACT ! !Use the Max Rimpull only, where the Application and Job requirements ask for it ! - This can be easily achieved by "hitting" the switch on top of the lift lever. - Hit the switch again, and the VCTC will return to the Capacity given by the control lever position.CATERPILLAR MINING BUSINESS UNIT COPYRIGHT 1995 CATERPILLAR ALL RIGHTS RESERVED