Starting Motor – Delco 50-MT

Illustration 1 g00697657

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 2 g00697684

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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