Benjamin Posted August 17, 2014 Report Share Posted August 17, 2014 (edited) I am sure most of you know about the Allison HT740 and HT747 transmissions, but the lower-rung MT644 and MT647 are not quite fondly as remembered. These share some of the same parts, such as torque converters. The MT644 was designed for engines up to 300 hp and 780 lb/ft of torque, whereas the later MT647 ups the input torque rating to 950 lb/ft. But for transit buses, these ratings will be different; for now I know the input hp limit for bus engines is 250. The MT648 was the electronically-controlled equivalent of the MT647. Torque converter ratios are 2.21 (TC495) and 1.92 (TC494). The HT740 was designed for engines up to 425 hp and 1300 lb/ft of torque, but in transit buses those ratings are reduced to 350 hp and 1100 lb/ft. The HT747, with its special three-gear pump for better coolant flow, is used only in transit buses and is rated for engines producing up to 350 hp and 1100 lb/ft. The HT741 and HT748 are the respective electronic equivalents of the HT740 and HT747. Torque converter ratios are 3.04 (TC470), 2.21 (TC495), 2.09 (TC499) and 1.83 (TC496, not available for HT747). I also want to know whether or not any buses that originally came with the MT644 or MT647 were changed to the HT747 or HT748 transmissions for durability reasons shortly after initial delivery or during their mid-life overhaul? So far I know a few buses had swapped out their MT644 or MT647 transmissions for HT747s or HT748s: Timmins Transit (Timmins, ON) 1982 Orion I 01.504 52-54 (54 was later resold to Ajax Transit as 2044) Mississauga Transit (Mississauga, ON) 1983 Orion I 01.504 8401-8404 Mississauga Transit 1984 Orion I 01.506 8405-8416 (8416 was resold to the National Research Council shortly after initial delivery) Mississauga Transit 1985 Orion I 01.508 8501 (replaced 8416) Vaughan Transit (Vaughan, ON) (later York Region Transit) 1987 Orion I 01.502 517-518 (original 6V71N engines were also reportedly changed to 6V92TA MUI's) University Transit Service (Charlottesville, VA) 1983 Orion I 01.506 5139-5239 and 5337 ~Ben Edited September 5, 2014 by Benjamin Link to comment Share on other sites More sharing options...
Detroit Diesel 6V92TA Posted August 20, 2014 Report Share Posted August 20, 2014 Which T-drive Allison transmission did most circa 1987 MCI 102AW3's have? Link to comment Share on other sites More sharing options...
Benjamin Posted August 20, 2014 Author Report Share Posted August 20, 2014 Which T-drive Allison transmission did most circa 1987 MCI 102AW3's have? They used Allison HT740 transmissions if the engine was non-DDEC (Detroit Diesel electronic controls), while for DDEC-equipped 6V92TAs the HT741 ATEC (Allison Transmission electronic controls) was used. ~Ben Link to comment Share on other sites More sharing options...
Detroit Diesel 6V92TA Posted August 20, 2014 Report Share Posted August 20, 2014 They used Allison HT740 transmissions if the engine was non-DDEC (Detroit Diesel electronic controls), while for DDEC-equipped 6V92TAs the HT741 ATEC (Allison Transmission electronic controls) was used. ~Ben Okay thanks. I just wanted to confirm that they didn't use HTB-748's. Link to comment Share on other sites More sharing options...
Benjamin Posted September 5, 2014 Author Report Share Posted September 5, 2014 (edited) How do I incorporate tables created in Microsoft Excel? ~Ben Edited September 5, 2014 by Benjamin Link to comment Share on other sites More sharing options...
Detroit Diesel 6V92TA Posted September 5, 2014 Report Share Posted September 5, 2014 How do I incorporate tables created in Microsoft Excel? ~Ben Tables? I think you would actually have to create the tables in word to be able to paste it on here, unless the button that allows the printing of tables in excel allows you to paste it on here. I forgot the button name at this momment. I may be able to check in a little while. Link to comment Share on other sites More sharing options...
Benjamin Posted September 5, 2014 Author Report Share Posted September 5, 2014 Here's one I did. ~Ben Link to comment Share on other sites More sharing options...
Benjamin Posted September 17, 2014 Author Report Share Posted September 17, 2014 (edited) Here are the official MT(B)644/647 ratings: GENERAL RATING Max input power: 250 hp (186 kW) Max input torque: 780 lb/ft (1058 N-m) Max input turbine torque: 1365 lb/ft (1851 N-m) Vehicle weight: Up to 55,000 lbs (24,948 kg) GVW or GCW TRANSIT BUS AND AIRPORT SHUTTLE BUS RATING Max input power: 235 hp (175 kW)Max input torque: 740 lb/ft (1003 N-m) Max input turbine torque: 1350 lb/ft (1830 N-m) Vehicle weight: Up to 42,000 lbs (19,051 kg) GVW EMERGENCY VEHICLE RATING Max input power: 300 hp (224 kW) Max input torque: 780 lb/ft (1058 N-m) Max input turbine torque: 1420 lb/ft (1926 N-m) Vehicle weight: Up to 55,000 lbs (24,948 kg) GVW INTERCITY COACH AND SCHOOL BUS RATING Max input power: 300 hp (224 kW) Max input torque: 780 lb/ft (1058 N-m) Max input turbine torque: 1365 lb/ft (1851 N-m) Vehicle weight: Up to 42,000 lbs (19,051 kg) GVW HEAVY TRUCK RATING Max input power: 250 hp (186 kW) Max input torque: 625 lb/ft (847 N-m) Max input turbine torque: 1365 lb/ft (1851 N-m) Vehicle weight: Up to 73,280 lbs (33,240 kg) GVW or GCW MOTOR HOME RATING Max input power: 300 hp (224 kW) Max input torque: 780 lb/ft (1058 N-m) Max input turbine torque: 1365 lb/ft (1851 N-m) Vehicle weight: Up to 42,000 lbs (19,051 kg) GVW Input speed (all): 2000-3000 RPM Source: the one and only Allison Transmission MT(B)644, 647 and 654CR Service Manual ~Ben Edited September 19, 2014 by Benjamin Link to comment Share on other sites More sharing options...
Benjamin Posted September 19, 2014 Author Report Share Posted September 19, 2014 (edited) Allison MT(B)654CR ratings: GENERAL RATING Max input: 250 hp (186 kW) Max torque: 780 lb/ft (1058 N-m) Max turbine torque: 1365 lb/ft (1851 N-m) Input speed: 1800-3000 RPM* Vehicle weight: Up to 55,000 lbs (24,948 kg) GVW or GCW TRANSIT/SHUTTLE BUS Max input: 235 hp (175 kW) Max torque: 740 lb/ft (1003 N-m) Max turbine torque: 1350 lb/ft (1830 N-m) Input speed: 2000-3000 RPM* Vehicle weight: Up to 42,000 lbs (19,051 kg) GVW EMERGENCY VEHICLES Max input power: 305 hp (227 kW) Max input torque: 975 lb/ft (1322 N-m) Max input turbine torque: 1735 lb/ft (2352 N-m) Input speed: 1800-3000 RPM* Vehicle weight: Up to 55,000 lbs (24,948 kg) GVW INTERCITY COACH & SCHOOL BUS RATING Max input power: 300 hp (224 kw) Max input torque: 780 lb/ft (1058 N-m) Max input turbine torque: 1365 lb/ft (1851 N-m) Input speed: 1800-3000 RPM* Vehicle weight: Up to 42,000 lbs (19,051 kg) GVW HEAVY TRUCK RATING Max input power: 250 hp (186 kW) Max input torque: 625 lb/ft (847 N-m) Max input turbine torque: 1365 lb/ft (1851 N-m) Input speed: 2000-3000 RPM* Vehicle weight: Up to 73,280 lbs (33,240 kg) GVW or GCW MOTORHOME RATING Max input power: 305 hp (227 kW) Max input torque: 975 lb/ft (1322 N-m) Max input turbine torque: 1735 lb/ft (2352 N-m) Input speed: 2000-3000 RPM* Vehicle weight: Up to 42,000 lbs (19,051 kg) GVW *Input speed 2600 RPM maximum on models equipped with retarder. Source: the official Allison Transmission MT(B)644, 647 and 654CR Service Manual (as usual) ~Ben Edited September 19, 2014 by Benjamin Link to comment Share on other sites More sharing options...
Detroit Diesel 6V92TA Posted October 11, 2014 Report Share Posted October 11, 2014 Was it possible to have a combination of a Cummins L10G and an Allison HTB-748 in an Orion V? This page (http://www.cptdb.ca/wiki/index.php?title=Port_Authority_of_Allegheny_County) has this combination, but I am not sure how corrected that is. Link to comment Share on other sites More sharing options...
Benjamin Posted October 11, 2014 Author Report Share Posted October 11, 2014 Was it possible to have a combination of a Cummins L10G and an Allison HTB-748 in an Orion V? This page (http://www.cptdb.ca/wiki/index.php?title=Port_Authority_of_Allegheny_County) has this combination, but I am not sure how corrected that is. Yes, but as the engine is not electronically controlled the HT747 would be a more acceptable transmission. ~Ben Link to comment Share on other sites More sharing options...
Detroit Diesel 6V92TA Posted October 11, 2014 Report Share Posted October 11, 2014 Yes, but as the engine is not electronically controlled the HT747 would be a more acceptable transmission. ~Ben Thanks. Link to comment Share on other sites More sharing options...
Kale96 Posted November 4, 2015 Report Share Posted November 4, 2015 NYCTA's 1993 BIA Orion Vs #101-298, #301-316 originally had Detroit Diesel Series 92 Engine & Allison HT-747 ATEC Transmissions Link to comment Share on other sites More sharing options...
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