793B Off-Highway Truck Power Train Caterpillar

Torque Converter and Transmission Pressure Chart

Usage:

793B 1HL

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Table 1
Nominal Engine Speed At Shift Points
	Released Service Brakes or Retarder	Engaged Service Brakes or Retarder
Upshift	Engine Speed (rpm)	Engine Speed (rpm)
1L to 2	1855 ± 30	1950 ± 30
2 to 3	1855 ± 30	1950 ± 30
3 to 4	1840 ± 30	1935 ± 30
4 to 5	1840 ± 30	1935 ± 30
5 to 6	1840 ± 30	1935 ± 30

	Released Service Brakes or Retarder	Engaged Service Brakes or Retarder
Downshift	Engine Speed (rpm)	Engine Speed (rpm)
6 to 5	1290 ± 30	1355 ± 30
5 to 4	1290 ± 30	1355 ± 30
4 to 3	1290 ± 30	1355 ± 30
3 to 2	1290 ± 30	1355 ± 30
2 to 1L	1300 ± 30	1370 ± 30
1L to 1C	1250 ± 30	1250 ± 30

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Table 2
Speed	Engaged Clutches	Torque Converter Drive	Direct Drive (Engaged Lockup Clutch)
Neutral-1	3	X	-
Neutral-2	1	X	-
Reverse	1 and 6	X	-
First Gear	1 and 5	X	X
Second Gear	2 and 5	-	X
Third Gear	1 and 4	-	X
Fourth Gear	2 and 4	-	X
Fifth Gear	1 and 3	-	X
Sixth Gear	2 and 3	-	X

Specifications for the Torque Converter

Outlet Relief Valve

Note: Refer to the Power Train Testing and Adjusting, "Relief Valve (Torque Converter Outlet) Pressure - Test and Adjust" for the proper procedure to adjust the torque converter outlet relief valve.

Pressure setting for the outlet relief valve on a test bench ... 345 ± 15 kPa (50 ± 2 psi)

Torque converter outlet pressure at stall speed ... 345 to 552 kPa (50 to 80 psi)

Torque converter stall speed at operating temperature ... 1672 ± 50 rpm

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Table 3
Spacer Chart For The Outlet Relief Valve
Pt. No. For The Spacers	Thickness Of The Spacers	Change In Pressure As A Result Of One Spacer
5M-9624 Spacer	0.25 mm (0.01 inch)	5 kPa (0.73 psi)
5M-9623 Spacer	0.90 mm (0.035 inch)	18 kPa (2.61 psi)

Inlet Relief Valve

Pressure setting for the inlet relief valve ... 930 ± 35 kPa (135 ± 5 psi)

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Table 4
Spacer Chart For The Inlet Relief Valve
Pt. No. For The Spacers	Thickness Of The Spacers	Change In Pressure As A Result Of One Spacer
5M-9624 Spacer	0.25 mm (0.01 inch)	14 kPa (2.0 psi)
5M-9623 Spacer	0.90 mm (0.035 inch)	49 kPa (7.1 psi)

Torque Converter Hydraulic Filter

Pressure setting for the bypass valve ... 140 kPa (20 psi)

Torque Converter Screen

Pressure setting for the bypass valve ... 125 ± 30 kPa (18 ± 4 psi)

Lockup Clutch and Synchronizing Valve

Pressure Reduction Valve

Note: Refer to the Power Train Testing and Adjusting, "Torque Converter Lockup Clutch Pilot Pressure - Test and Adjust" for the proper procedure to adjust the pilot pressure for the torque converter lockup clutch and synchronizing valve.

Pilot pressure at low idle ... 1725 ± 70 kPa (250 ± 10 psi)

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Table 5
Chart Of Shims For The Pressure Reduction Valve In The Torque Converter Lockup Clutch
Pt. No. For The Shims	Thickness Of The Shims	Change In Primary Pressure As A Result Of One Shim
5J-2721 Shim	0.13 mm (0.005 inch)	10 kPa (1.4 psi)
6J-3993 Shim	0.25 mm (0.01 inch)	19 kPa (2.8 psi)
5J-1036 Shim	0.80 mm (0.031 inch)	60 kPa (8.7 psi)

Modulation Reduction Valve

Note: Refer to the Power Train Testing and Adjusting, "Torque Converter Lockup Clutch Primary Pressure - Test and Adjust" for the proper procedure to adjust the primary pressure for the torque converter lockup clutch and synchronizing valve.

Lockup clutch primary pressure at low idle ... 1030 ± 35 kPa (150 ± 5 psi)

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Table 6
Chart Of Shims For The Modulation Reduction Valve In The Torque Converter Lockup Clutch
Pt. No. For The Shims	Thickness Of The Shims	Change In Primary Pressure As A Result Of One Shim
8J-4452 Shim	0.12 mm (0.005 inch)	10 kPa (1.4 psi)
2S-0675 Spacer	0.40 mm (0.016 inch)	32 kPa (4.7 psi)
9J-1330 Shim	0.79 mm (0.031 inch)	62 kPa (9.0 psi)

Note: Refer to the Power Train Testing and Adjusting, "Torque Converter Lockup Clutch Maximum Pressure - Test" for the proper procedure to check the maximum pressure for the torque converter lockup clutch.

Maximum clutch pressure at 1300 rpm ... 2205 ± 70 kPa (320 ± 10 psi)

Transmission

Pressure Control Valve

Note: Refer to the Power Train Testing and Adjusting, "Transmission Hydraulic Control Primary Clutch Pressure - Test and Adjust" for the proper procedure to adjust the primary pressure for the transmission hydraulic control.

Note: Refer to the Power Train Testing and Adjusting, "Transmission Hydraulic Control Clutch Pressure - Test" for the proper procedure to check the maximum pressure for the transmission clutches.

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Table 7
Station⁽¹⁾	A	B	C	D⁽²⁾	E	F	G
Engaged Clutch	2	1	3	-	4	5	6
Type Of Test	Pressure
Clutch Pressure At High Idle In Torque Converter Drive⁽³⁾	-	2425 kPa (352 psi)	2470 kPa (358 psi)	-	-	2720 kPa (395 psi)	2805 kPa (407 psi)
Clutch Pressure At Low Idle In Torque Converter Drive⁽³⁾	-	2400 kPa (348 psi)	-	-	-	2585 kPa (375 psi)	2585 kPa (375 psi)
Clutch Pressure At High Idle in Direct Drive	1620 kPa (235 psi)	1620 kPa (235 psi)	1620 kPa (235 psi)	-	1620 kPa (235 psi)	1620 kPa (235 psi)	-
Primary Clutch Pressure At Low Idle⁽⁴⁾	525 kPa (76 psi)	475 kPa (69 psi)	480 kPa (70 psi)	-	425 kPa (62 psi)	450 kPa (65 psi)	425 kPa (62 psi)

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⁽¹⁾	Station "H" is not used.
⁽²⁾	Station "D" does not control a clutch. When the lockup clutch solenoid is activated, Station "D" reduces the pressure setting of the dual stage relief valve. The action of Station "D" on the ICM transmission hydraulic control maintains the oil in the clutch supply rail at a reduced pressure. Refer to the Testing and Adjusting, "Transmission Hydraulic Control (Pressure Pack) - Test and Adjust" for the proper procedure to adjust Station "D".
⁽³⁾	The tolerance is + 240 − 100 kPa (+ 35 − 15 psi).
⁽⁴⁾	The tolerance is + 50 − 35 kPa (+ 7 − 5 psi).

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Table 8
Shims For The Pressure Control Valve Pressure Change Per Shim⁽¹⁾
Station⁽²⁾	A	B	C	D⁽³⁾	E	F	G
Clutch Engaged	2	1	3	-	4	5	6
Thickness of Shim	Pressure Change	Pressure Change	Pressure Change	Pressure Change	Pressure Change	Pressure Change	Pressure Change
5J-2721 Shim
0.13 mm (0.005 inch)	19 kPa (2.8 psi)	20 kPa (2.9 psi)	20 kPa (2.9 psi)	Refer to Table 11.	17 kPa (2.5 psi)	19 kPa (2.7 psi)	19 kPa (2.8 psi)
6J-3993 Shim
0.25 mm (0.010 inch)	39 kPa (5.6 psi)	41 kPa (5.9 psi)	41 kPa (5.9 psi)	Refer to Table 11.	35 kPa (5.1 psi)	37 kPa (5.3 psi)	39 kPa (5.6 psi)
4M-1751 Spacer
0.41 mm (0.016 inch)	62 kPa (9.0 psi)	65 kPa (9.4 psi)	65 kPa (9.4 psi)	Refer to Table 11.	56 kPa (8.1 psi)	59 kPa (8.6 psi)	62 kPa (9.0 psi)
5J-1036 Shim
0.80 mm (0.031 inch)	120 kPa (17.4 psi)	125 kPa (18.2 psi)	125 kPa (18.2 psi)	Refer to Table 11.	109 kPa (15.8 psi)	114 kPa (16.6 psi)	120 kPa (17.4 psi)

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⁽¹⁾	Do not change the amount of shims unless you are adjusting the primary pressure of the transmission clutches.
⁽²⁾	Station "H" is not used.
⁽³⁾	Station "D" does not control a clutch. When the lockup clutch solenoid is activated, Station "D" reduces the pressure setting of the dual stage relief valve. The action of Station "D" on the ICM transmission hydraulic control maintains the oil in the clutch supply rail at a reduced pressure. Refer to the Testing and Adjusting, "Transmission Hydraulic Control (Pressure Pack) - Test and Adjust" for the proper procedure to adjust Station "D".

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Table 9
Specifications And Identification Of The Components Of The Pressure Control Valve
Location Of The Load Piston Body⁽¹⁾	A	B	C	D	E	F	G
Thickness Of The Load Piston Orifice	2.54 mm (.100 inch)	4.58 mm (.180 inch)	2.54 mm (.100 inch)		2.54 inch (.100 inch)	6.60 mm (.260 inch)	6.60 mm (.260 inch)
Color Of The Outer Spring Of The Load Piston	Light green color	Light green color	Light green color		Light green color	Light green color	Light green color
Color Of The Inner Spring Of The Load Piston	Light green color	Light blue color	Light blue color		Orange color	Yellow color	Light green color
Size Of The Decay Orifice	1.19 mm (0.47 inch)	1.40 mm (.055 inch)	1.98 mm (.078 inch)		1.57 mm (.062 inch)	1.40 mm (.055 inch)
Color Of The Decay Orifice	Blue color	Yellow color	Red color		Green color	Yellow color

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⁽¹⁾	The location of the load piston body is identical to the location of the station. Station "H" is not used.

Transmission Hydraulic Control

Note: Refer to the Power Train Testing and Adjusting, "Transmission Hydraulic Control (Pressure Pack) - Test and Adjust" for the proper procedure to adjust the pressures in the selector and pressure control valve.

Pressure Of The Transmission Charging Pump Section In Torque Converter Drive

Minimum pressure of the transmission charging pump section at low idle in torque converter drive ... 2515 kPa (365 psi)

Maximum pressure of the transmission charging pump section at high idle in torque converter drive ... 3065 kPa (445 psi)

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Table 10
Chart of Spacers For The Dual Stage Relief Valve⁽¹⁾
Pt. No. For The Spacers	Thickness Of The Spacers	Change In Pressure As A Result Of One Spacer
145-0105 Spacer	0.25 mm (0.010 inch)	41 kPa (6.0 psi)
145-0106 Spacer	0.90 mm (0.035 inch)	145 kPa (21.0 psi)
145-0107 Spacer	1.60 mm (0.063 inch)	261 kPa (37.9 psi)

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⁽¹⁾	When the lockup clutch is not energized, use these spacers to adjust the pump pressure.

Pressure Of The Clutch Supply Rail In Direct Drive

Pressure of the clutch supply rail at medium idle in direct drive ... 1620 ± 70 kPa (235 ± 10 psi)

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Table 11
Chart Of Shims For Station "D"⁽¹⁾
Pt. No. For The Shims	Thickness Of The Shims	Change In Pressure As A Result Of The Shims
5J-6153 Shim	0.18 mm (0.007 inch)	17 kPa (2.5 psi)
8M-2932 Shim	0.41 mm (0.016 inch)	39 kPa (5.7 psi)
8H-9190 Shim	0.76 mm (0.030 inch)	74 kPa (10.7 psi)

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⁽¹⁾	When the lockup clutch solenoid is energized, use these shims to change the pressure in the clutch supply rail.

Pressure Of The Transmission Charging Pump Section In Direct Drive

Pressure of the transmission charging pump section at medium idle in direct drive ... 2310 ± 70 kPa (335 ± 10 psi)

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Table 12
Chart Of Spacers For The Priority Reduction Valve⁽¹⁾
Pt. No. For The Spacers	Thickness Of The Spacers	Change In Pressure As A Result Of The Spacers
5M-3492 Spacer	0.25 mm (0.010 inch)	25 kPa (3.6 psi)
7M-1397 Spacer	0.91 mm (0.036 inch)	89 kPa (12.9 psi)

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⁽¹⁾	When the lockup clutch solenoid is energized, use these spacers to adjust the pump pressure.

Transmission Lubrication Pressure

Note: Refer to the Power Train Testing and Adjusting, "Lubrication Relief Valve (Transmission) - Test" for the proper procedure to check the pressure for the lubrication of the transmission.

Transmission lubrication pressure at high idle ... 160 ± 50 kPa (23 ± 7 psi)

Transmission lubrication pressure at low idle ... 5 to 65 kPa (0.7 to 9.4 psi)

Relief valve setting on a test bench ... 240 ± 35 kPa (35 ± 5 psi)