Starting Motor - Delco 50-MT Caterpillar


Starting Motor

Usage:

769C 01X


Illustration 1g00697657
Side view of the 50-MT series
(1) Nut (battery terminal)
(2) Screw (terminal assembly)
(3) Bolts (solenoid mounting)
(4) Pinion
(5) Bolts (rear frame)
(6) Screw (field winding) (brush lead)
(7) Commutator
(8) Brushes
(9) Laminated core
(10) Screws (field winding)
(11) Bolts (shift lever housing)
(12) Screw (pinion drive housing)


Illustration 2g00697684
Front view of the solenoid for a 50 MT series
(1) Nut (battery terminal)
(2) Screw (terminal assembly)
(13) Nuts (terminal)

Table 1
50-MT Complete Starting Motor Specifications 
Rated Voltage  24V  32V  64V 
Solenoid Winding 
Pull-In Resistance  .43 to .56 Ω  1.2 to1.43 Ω  3.56 to 3.97 Ω 
Hold-In Resistance  2.9 min Ω  5.3 to 7.0 Ω  17.1 to 18.9 Ω 
Pull-In Current  9.0 to 11.5 Amp at 5 V  7.0 to 8.3 Amp at 10 V  7.0 to 8.3 Amp at 10 V 
Hold-In Current  6.8 Amp max at 20 V  4.0 to 5.3 Amp at 28 V  4.0 to 5.3 Amp at 28 V 
No Load Test 
Voltage  20V  30V  32V 
Current (max)  120 Amp  125 Amp  90 Amp 
Speed (min)  5500 rpm  7500 rpm  5500 rpm 
Load Test 
Voltage  18V  24V  NA 
Current (max)  750 Amp  700 Amp  NA 
Speed (min)  1200 rpm  1100 rpm  NA 
Commutator (7) 
Diameter   58.7 to 58.9 mm (2.34 to 2.32 inch)  58.7 to 58.9 mm (2.34 to 2.32 inch)  58.7 to 58.9 mm (2.34 to 2.32 inch) 
Diameter (min)  56.7 mm (2.23 inch)  56.7 mm (2.23 inch)  56.7 mm (2.23 inch) 
Depth Of Insulation Between Commutator Bars (min)  0.64 mm (.025 inch)  0.64 mm (.025 inch)  0.64 mm (.025 inch) 
Brush (8) 
Length  19.1 to 19.8 mm (.75 to .78 inch)  19.1 to 19.8 mm (.75 to .78 inch)  19.1 to 19.8 mm (.75 to .78 inch) 
Length (min)  10 mm (.4 inch)  10 mm (.4 inch)  10 mm (.4 inch) 
Pinion Clearance (4)   9.1 ± 0.8 mm (0.36 ± 0.03 inch)  9.1 ± 0.8 mm (0.36 ± 0.03 inch)  9.1 ± 0.8 mm (0.36 ± 0.03 inch) 
Maximum Total Indicator Runout (TIR) 
Commutator (7)  0.13 mm (.005 inch)  0.13 mm (.005 inch)  0.13 mm (.005 inch) 
Laminated Core (9)  0.13 mm (.005 inch)  0.13 mm (.005 inch)  0.13 mm (.005 inch) 
Torques 
Terminal Nuts (1)  30.5 ± 3 N·m (22.5 ± 2.2 lb ft)  30.5 ± 3 N·m (22.5 ± 2.2 lb ft)  30.5 ± 3 N·m (22.5 ± 2.2 lb ft) 
Terminal Nuts (13)  2.25 ± .25 N·m (20 ± 2 lb in)  2.25 ± .25 N·m (20 ± 2 lb in)  2.25 ± .25 N·m (20 ± 2 lb in) 
Terminal Screw (2)  2.25 ± .25 N·m (20 ± 2 lb in)  2.25 ± .25 N·m (20 ± 2 lb in)  2.25 ± .25 N·m (20 ± 2 lb in) 
Solenoid Mounting Bolts (3)  12.2 ± 2.7 N·m (108 ± 24 lb in)  12.2 ± 2.7 N·m (108 ± 24 lb in)  12.2 ± 2.7 N·m (108 ± 24 lb in) 
Rear Frame Bolts (5)  12.2 ± 2.7 N·m (108 ± 24 lb in)  12.2 ± 2.7 N·m (108 ± 24 lb in)  12.2 ± 2.7 N·m (108 ± 24 lb in) 
Shift Lever Housing Bolts (11)  12.2 ± 2.7 N·m (108 ± 24 lb in)  12.2 ± 2.7 N·m (108 ± 24 lb in)  12.2 ± 2.7 N·m (108 ± 24 lb in) 
Pinion Drive Housing Screw (12)  20 ± 3 N·m (177 ± 27 lb in)  20 ± 3 N·m (177 ± 27 lb in)  20 ± 3 N·m (177 ± 27 lb in) 
Field Winding And Brush Lead Screw (6)  2.9 ± 1.0 N·m (26 ± 9 lb in)  2.9 ± 1.0 N·m (26 ± 9 lb in)  2.9 ± 1.0 N·m (26 ± 9 lb in) 
Field Winding Screws (10)  20.3 ± 2.3 N·m (180 ± 20 lb in)  20.3 ± 2.3 N·m (180 ± 20 lb in)  20.3 ± 2.3 N·m (180 ± 20 lb in) 
Starting Motor Weight  35.4 kg (78 lb)  35.4 kg (78 lb)  35.4 kg (78 lb) 

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