METER GROUP 1P3835 - Caterpillar

Note: All transmission control valves, 314-9930, 261-3383, and 261-3378 should be modified per Service Magazine, SEPD1360, "Hydraulic Control Modifications for TH48-E80 Petroleum Transmission and SPF343C Pumper Transmission {3074, 3083, 3167}".
Table 1
TH48-E80 ICM Valve History
Control Group 8 Speed No Warm up Feature 7 Speed with Warm-up Feature
258-8741 314-9942
Valve Group 261-3372 367-2223 314-9940 367-2233
Serial Numbers 1-845 846-Up 1-845 846-Up
Pressure Control Valve 261-3378 367-2179 261-3378 367-2179
Selector Valve 261-3383 375-5500 314-9930 375-5499
Manifold 261-3377 261-3377 261-3377 261-3377 Note: The valve group for serial numbers 1-845 will be identical to the valve group for serial numbers 846 and up after updating per service magazine SEPD1360.Note: The valve group was updated to reduce clutch power and energy during the shift and increase shift speed to reduce transmission output speed drop during shifting.
Illustration 1 g01710716
Transmission pressure control valve
(1) Drain passages
(2) Passage for pump oil
(3) Passage to the No. 5 clutch
(4) Drain passage (six)
(5) Springs
(6) Load piston (six)
(7) Passage in the selector piston
(8) Selector piston (six)
(9) Pilot oil passage (six)
(10) Modulation reduction valve spring (six)
(11) Modulation reduction valve (six)
(12) Ball check valve
(13) Load piston orifice
(14) Load piston plug (six)
(15) Decay orifice (six)
(16) Drain passage (six)
(17) Selector piston plug (six)
(18) Load piston body (six)
(19) Passage to the No. 4 clutch
(20) Passage to the No. 2 clutch
(21) Passage to the No. 1 clutch
(22) Passage to the No. 6 clutch
(23) Passage to the No. 3 clutch
(24) Passage from the transmission charging section
(A) Identification of load piston body
(B) Identification of load piston body
(C) Identification of load piston body
(D) This load piston body is not used.
(E) Identification of load piston body
(F) This load piston body is not used.
(G) Identification of load piston body
(H) Identification of load piston body The pressure control valve has six modulation reduction valves (11). There is one modulation reduction valve for each clutch in the transmission. Each modulation reduction valve acts separately. This is known as Individual Clutch Modulation (ICM). The modulation reduction valves control the amount of pressure that will be used for clutch engagement and for the release of the clutch. The modulation reduction valves also determine the duration of clutch engagement.Each load piston body has an identification letter for the purposes of Disassembly and Assembly. Pilot passages (9) are connected to passages from the rotary selector spool of the selector and pressure control valve. Pump oil from the selector and pressure control valve is in passage (2). Drain passages (1) are connected to the transmission case reservoir.All of the modulation reduction valves operate in a similar way, so only the basic operation is provided.The Beginning of a Shift and the Clutch is Filling
Illustration 2 g00535121
Modulation reduction valve at the beginning of a shift
(1) Drain passage
(2) Passage for pump oil
(3) Passage to clutch
(4) Drain passage
(5) Springs
(6) Load piston
(7) Passage in the selector piston
(8) Selector piston
(9) Pilot passage
(10) Spring
(11) Modulation reduction valve
(12) Ball check valve
(13) Load piston orifice
(14) Load piston plug
(15) Decay orifice
(16) Drain passage
(17) Selector piston plug
(18) Load