The pre-engaged starter motor is a type of starter motor that was developed to reduce gear wear and gear damage associated with inertia starters. It is fitted with a relay valve that controls the movement of the pinion, which moves along the shaft until it comes into contact with the toothed ring-gear. The pinion interlocks with the ring-gear before rotating to crank the engine.
Inertia starters are common in 1960s classic cars and work by spinning a pinion that drives itself up the main shaft and engages with the ring gear. When it mates, it produces a distinctive metallic grating sound, which cranks the ring gear around. Pre-engaged starters are more sophisticated, with a solenoid that pushes the pinion to engage with the ring gear before another solenoid supplies power to the starter motor.
The starter motor is powered by the car’s main 12-volt battery, which requires very high electric current to turn over the engine. To achieve ATEX approval, the starter motor must have sufficient power. If the battery is discharged, the lights in a car might work but it won’t have enough power.
Pre-engaged starter motors are commonly used for high-compression engines with automatic transmission systems, such as large petrol engines. They are equipped with a relay valve that controls the movement of the pinion, which moves along the shaft until it comes into contact with the toothed ring-gear.
In summary, pre-engaged starter motors are designed to overcome the problems and gear damage associated with inertia starters. They are more sophisticated and require a higher power supply than inertia starters.
📹 Inside a Pre-engaged starter motor
This starter motor was developed to overcome the problems and gear damage associated with inertia starter motors. This is the …
What is a pre-engaged starter?
The starter motor has a relay valve that controls the pinion. When the starter motor is activated, the pinion moves along the shaft until it touches the gear. The pinion and ring gear interlock before the engine is cranked. As the engine speeds up, the starter motor is protected from over-speed by a free wheel clutch. At this point, the spring pulls the pinion back to its starting position. Watch this video to see the pre-engaged mechanism in action.
How does inertia affect a motor?
Raising motor inertia increases total inertia by 50%. This reduces the total acceleration by 50%, or requires 50% more torque to maintain it. Higher torque costs more. The technique is commonly used because it works well. One common mistake is thinking that the load-inertia-to-motor inertia ratio is best when the two are the same. This is based on the idea of optimal power transfer. The idea is that the gear ratio that transfers the most power from the motor to the load is the one that makes the reflected load inertia equal to the motor inertia. This is interesting, but it doesn’t affect how motors and gear ratios are chosen in practice because the assumption that the motor inertia is fixed is usually wrong. Each time the gear ratio increases, the required torque from the motor decreases, allowing use of a smaller motor. Matching motor and load inertia reduces resonance problems. Matching the inertias is oversimplified. A larger motor improves resonance but costs more. A responsive control system needs less load inertia than motor inertia. Ratios of 3–5 are common in typical servo applications, and larger ratios work in pedestrian applications. Nimble machines often need matched loads. The highest-bandwidth applications require that the load inertia be no larger than about 70% of the motor inertia. The load-inertia-to-motor-inertia ratio depends on the machine’s compliance. Stiffer machines can handle larger load inertias. Direct-drive systems allow load-inertia-to-motor-inertia ratios greater than 100 with high bandwidth.
What is the purpose of a one way clutch fitted to a pre engaged starter motor?
The starter drive clutch is a roller clutch used in a starter motor to crank internal combustion engines. The starter drive clutch transfers torque from an electrical motor to a ring gear on a cranking shaft in the engine, which cranks the engine. The clutch also protects the starter from damage from high loads and speeds. Two major problems with the starter drive are slippage and cracking. If the starter doesn’t have enough torque, it slips. If the clutch barrel is under too much stress, it cracks. To avoid slippage, the clutch should be strong. But high torque capacity can also cause the barrel to crack. Higher torque capacity and lower hoop stress are two opposite design directions. The clutch design should be optimized. The best clutch design is one that has the most torque and the least stress on the barrel. The goal is to design a clutch that can handle the most torque and has the least stress on the barrel. To achieve this, we create an optimization model based on the clutch mechanism. A sensitivity analysis is used to select the most effective parameters for optimization. A constant strut angle is added to keep the strut angle the same when the clutch is working. Finally, a case study shows this design approach improved the clutch. SAE MOBILUS. Subscribers can view, annotate, and download all of SAE’s content. Learn more.
How does a starter motor solenoid work?
How does the starter solenoid work? The solenoid switch is a simple part of the starter motor. It has a battery, a pull-in and hold-in coil, and an iron plunger. When you start your car, the battery sends voltage to the solenoid, which creates a magnetic field. The magnetic field pulls the plunger into the core, completing the electric circuit. This makes the pinion and engine flywheel mesh and starts the engine. The hold-in coil uses a weaker magnetic field to keep the plunger in place. What Kills a Starter Motor? Starter motors don’t last forever. The starter motor gives your car the kick it needs to start, but it goes through a lot of stress and deteriorates over time. The pressure varies with the size and age of your car, but it will eventually stop working. You can make yours last longer. These checks and maintenance could get you more miles out of your car.
What are the disadvantages of inertia engaged starter motors?
Inertia starters are more efficient than standard starters because they don’t directly drive the engine. This allows for a lighter motor, cables, and batteries. Inertia starters were common in aircraft with large radial piston engines. The downside is that it takes longer to start the engine. It can take 10 to 20 seconds to spin up the flywheel. If the engine doesn’t start by the time the flywheel loses its inertia, try again.
Edit: Pneumatic. Some gas turbine and diesel engines use a pneumatic self-starter. In ground vehicles, the system has a geared turbine, an air compressor, and a pressure tank. Compressed air from the tank spins the turbine, which engages the ring gear on the flywheel. The engine runs the compressor to refill the tank. Aircraft with large gas turbine engines are typically started using a large volume of low-pressure compressed air from an auxiliary power unit. Another way to start an aircraft gas turbine engine is with a mobile ground-based pneumatic starting engine, called a start cart or air start cart.
What causes a starter solenoid to stay engaged?
The starter solenoid is stuck or there’s a short to power on the small wire connected to it. The small wire should only be powered when the key is in the start position. If it stays powered in the run position, the starter will stay engaged. If the starter solenoid sticks, the starter will stay running until it unsticks or the battery is disconnected. Unplug the wire from the starter solenoid and check it with a test light when the key is in the start position and then in the run position. The light should come on when the key is in the start position and go off when the key is in the run position.
How does a starter engage and disengage?
The starter motor has a Bendix gear that engages with the flywheel only when the starter is turning the engine. It disengages as the engine speeds up. There are two ways it does so. The inertia starter relies on the pinion’s reluctance to turn. The pinion is not fixed to the motor shaft. It is threaded on to it, like a nut on a bolt.
What does a one way clutch in a pre engaged starter motor do?
The one-way clutch prevents the starter motor from being driven too fast after the engine starts. In the engine starter mechanism, the outer race of the one-way clutch transmits a driving force from the starter motor to the engine’s crank shaft. This seal is between the flange and the inner race of the clutch. However, the flange portion extending in the axial direction is positioned to allow for the oil seal, so the length of the engine starter mechanism in the axial direction cannot be shortened, which has caused problems with space saving and cost reduction.
What are the advantages of a pre-engaged starter motor?
Pre-engaged starter motors are important in areas covered by ATEX safety regulations because sparks from the starting system could be dangerous. IPUs pre-engaged starter motors meet ATEX safety standards because they don’t spark. Jetstream 5 Air Starter Motor. The Jetstream 5 air start motor is a pre-engaged starter motor for engines up to 80 litres. It’s ideal for explosive atmospheres like underground mines because it’s ATEX compliant.
M22 Pre-engaged Hydraulic Starter Motor. The IPUs M22 pre-engaged hydraulic starter motor is reliable, no matter the environment. The IPUs M22 hydraulic starter motors are ATEX-approved for use in gas and mining environments.
What is the difference between a pre-engaged starter motor and an inertia drive starter motor?
What is pre-engaged starting? Inertia and pre-engaged starting differ in that the latter only starts the high-speed rotation once the pinion is fully engaged with the ring gear. The pinion and ring gear don’t collide. The pinion is often controlled by a relay valve. This moves the pinion along the shaft until it connects with the ring gear. Once engaged, the full starting system pressure is released to crank the engine.
ATEX-approved hydraulic starter. If you operate an offshore platform or underground mine, ATEX certification means safety. The goal of the ATEX safety standard is to remove the risk of fires or explosions. To meet this goal, an engine starting system must use a pre-engaged starter motor.
What is the function of the solenoid on a pre-engaged starter motor?
It is the coil that connects the battery to the starter motor. All modern cars also use the starter solenoid to engage the starter pinion with the engine’s ring gear. The starter solenoid is sometimes called the starter relay, but many cars reserve that name for a separate relay. The ignition switch turns on the starter relay, which turns on the starter solenoid, which turns on the starter motor.
Operation An idle starter solenoid can get a big electric current from the car battery and a small one from the ignition switch. When the ignition switch is on, a current is sent through the starter solenoid. This makes the starter solenoid close a pair of heavy contacts, sending a large electric current through the starter motor, which starts the engine.
How does a starter motor engage?
Field coils: The field coils are around the armature. They create a magnetic field that interacts with the armature to produce torque. Solenoid: The solenoid engages the starter motor. When you turn the key, the solenoid connects the starter motor to the battery.
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- What is a Car Starter Motor?
A car starter motor is a small electric motor that starts the engine. The starter motor is linked to the flywheel in the engine bay. This makes it easy for the starter motor to move the engine. Turning the key starts the engine. Knowing this helps us understand how it helps the car engine work. The starter motor is simple but essential for starting your car. If the starter motor fails, you can’t start your car and you’ll need to get it towed to a mechanic.
📹 How an Engine Starter Motor Works
This video explains the working of a starter motor with relevant animations. The starter motor model shown here is a pre-engaged …
video is very good, but to be really, really perfect, the helicoidal spline is also there because the motor starts to spin before the pinion engages with the flywheel, so the helicoidal spline couteracts this initial rotation to have better mesh of the gears. The early start of the motor is to have it start with little to no load and then add the load later (we’re talking about milliseconds later) to reduce the current spike and prevent damage to the whole electrical system.
I haven’t been intimate with a starter assembly in a long time, since I’ve been driving newer cars instead of beaters but it was good seeing one again. Now, I don’t even know where the starter is on my fwd car. I can’t see it, I suspect it’s between the engine and the firewall covered with stuff. Cars were more honest and open back when I was working on them back in the 70s- 80s.
Very well presented and well thought out article. Thank you for this! There is only one caveat: the answer to the question at 1:12 “Why solenoid and contactor are used instead of directly connecting battery to the motor and reducing the complexity” is not because of high current demand of the motor. If we had this simplified circuit (like shown at 1:18), the motor would be always on, which obviously the electric motor should only run when we want to crank the engine until it starts. In any other instance this motor is turned off. Perhaps they meant why not to use any other switch instead of solenoid, which is designed to handle heavy currents. However, the way it is shown it would run contentiously.
another point: if you connect battery directly to the electric motor, because of the inertia the start will engage and you don’t even need that salenoid! extra other point: the salenoid is exactly a relay if you look closely! 30terminal:battery, 85:+12v from starter switch, 86 terminal: Ground, and 87 terminal is to the electric motor. 86&85 are x2 poles of the self
Sure there’s a good reason but why not combine the alternator AND starter and save weight while reducing parasitic drag on the engine? Why spin 2 things when you could spin 1 thing? Why have the weight of 2 things when you could save weight by having 1 thing start the engine AND generate electricity? Also it seems like combining the starter and alternator into 1 would reduce complexity and number of moving parts.
solinoids suck and ware out for no reason so it’s a good idea to wire both points on the solidoid to a bypass so when needed when you turn the key and nothing happens you can bypass the solinoid mechenism by putting both wire together or on a switch to forcefully start the motor or you can get a power probe and send power straight to the electric starter motor also bypassing the solinoid
Most starters haven’t worked that way for 70 years! Pre-engagement starters haven’t been used on ANY Japanese car since the 1950’s and NO MOPAR since the mid 1950’s! BENDIX starters have been used on ALL GM small block V-8’s since their inception and all Ford Cleveland, Windsor’s, and 4.6/5.0 liters. Would you like me to go to a salvage and take a modern starter off a car and photograph HOW it works? It sure doesn’t work like you show!!! I’m 68 years-old and worked in a service station as a YOUNG teen-ager and only saw a few cars in the 1960’s with that type starter, and most had STARTER PEDALS ON THE FLOOR and were three times older than I was!!!
Hi Iv got a Fiat 128 Rally 1974 My starter keep on cranking and not start at all, i had to pul battery wire to stop it. After days of strangle i find that the points plastic on it melt little and touching the earth. After fixed the points starter stop keep on cranking. And car starts 100% Thing that confuse me totaly. How can points that touch earth like my car did. Let the starter keep on cranking. How is that possible??? My coil got 3 wires on. 1. Ignition wire to + 2. Wire to points on – 3. Wire also on – (this wire i got no idee where it goes) Realy realy hope you can give me the answer on this. 😁😁😁
I just replaced my starter today and got me to thinking about how a starter actually works (after 44 years of driving lol). I get how the pinion is rotated a little to help it mesh with the flywheel when starting the engine. However, what I don’t understand is how does the flywheel not destroy the pinion as it gets pulled back? It just seems like the flywheel would tear up the pinion as it’s being pulled back towards the body of the starter. Anyone know the answer to this? Just curious.