851997 Volvo.Penta Screw

988F Service Manual, Operator Manual and Operating Tips - Video. TIB - March 10.1994 - Differences of match between 988B VCTC and 988F VCTC in regards to Engine Flywheel HP/Torque. TIB - August 27.92 - 988B/992C - How to use the VCTC correctly.Problem:
We have received reports from certain 988F applications, about poor engine recovery out of loaded engine deep lug.This situation can occur after a transmission directional shift, with a fully loaded bucket, activated implement hydraulics and steering, maximum VCTC rim-pull lever setting, and with the engine RPM's below 1200 RPM. - I.E - engine deep lug overload.DISCUSSION:As explained in earlier TiB's, the 988F is equipped with the 992C size VCTC. Hence - when used in the maximum Rimpull position, the power train represents a much bigger (in %) HP consumer on the engine then on the 988B in the same VCTC lever position. - In additon, the speeding up of the implement hydraulics has added an additional load on the engine as well. - The 3rd major HP consumer is the steering system and it's residual system pressure after actuating the steering. - The 988F engine, rated at 400HP/2000 RPM, can only cope with this kind of a HP demand, IF the engine RPM's are kept high at all times. - Keeping the engine RPM's high "at all times" is however not possible in all applications, - mainly due to possible spillage during directional shift "shocks".Solution:
If "lack of engine recovery" out of deep lug complaints are received from end-users, we recommend the following action:- Find out what the engine "load factor" is. - 32-38 ltrs/hr = Low Load Factor-44-49 ltrs/hr = Medium LF.- 60-66 Itrs/hr = High LF.- 86 ltrs/hr = 100% LF. - If the Load Factor is above 49 Itrs/hr disregard this solution. - Too short an engine life may result.-Increase the STATIC FULL LOAD FUEL SETTING by .50mm to 3.70 mm. - Do not make any change to the torque control group.-With all systems at "normal" operating temperatures, check/readjust the full load RPM to 2000 RPM, using the service manual procedure, the VCTC control lever and a continuity light. - If an adjustment is necessary, turn the High Idle screw on the governor until the full load RPM (2000) is within specs.-With all systems at normal operating temperatures measure the "loaded" acceleration time from "Low Idle" to Stall Speed. (4th speed forward) - Check at the same time for black acceleration smoke.-If the black acceleration smoke appears/is unacceptable,turn in the FARC control adjustment screw half a turn at a time, until the acceleration smoke / engine response time - are acceptable. -Make sure, the operator understands clearly how to adjust the VCTC/Rimpull correctly ! - For normal loading applications, the power train should NOT absorb more than maximum engine HP ! - I.E. - Stall speed = Full Load RPM. 3.70 mm of static full load fuel setting at 2000 RPM will increase the HP rating of the engine to 425 HP. - Under no circumstances should an even higher rating be selected.COSA HEAVY CONSTRUCTION AND MINING COPYRIGHT 1994 CATERPILLAR ALL RIGHTS RESERVED