u/Feisty_Reindeer7532

Hi everyone, I’m a mechanical engineering student currently writing a paper that compares the Bosch CP4.2 and Denso HP5D high-pressure common rail pumps.

I’ve easily found detailed diagrams, cross-sections, and even teardown photos for the Bosch CP4.2, which clearly show how the eccentric shaft drives the roller tappets and the plungers. For the Denso HP5D (and the closely related HP5), however, I’ve hit a wall – I can’t find a single clear illustration of its internal construction.

What I’m specifically looking for:

How rotary motion is converted into reciprocating plunger movement (cam ring with rollers vs. eccentric shaft)

How the roller tappet is prevented from rotating inside its bore

The second point is crucial for my comparison. In the CP4.2, one of the well-known catastrophic failure modes occurs when the roller tappet turns sideways, causing the roller to skid across the cam lobe rather than rolling – this destroys the pump and sends metal through the entire fuel system. I’m trying to understand exactly how Denso designed the HP5D to avoid this problem (or if it has a different weakness).

If anyone has access to a Denso service manual, an SAE paper, a training document, or even a personal photo of a disassembled pump that shows the cam ring, roller tappet, and anti-rotation feature, I’d be incredibly grateful. I’m also happy for any pointers on where to search – I’ve tried Denso’s public technical documents, Google Patents, and general image searches without success.

Thanks in advance for any help!

Hi everyone, I’m a mechanical engineering student currently writing a paper that compares the Bosch CP4.2 and Denso HP5D high-pressure common rail pumps.

I’ve easily found detailed diagrams, cross-sections, and even teardown photos for the Bosch CP4.2, which clearly show how the shaft drives the roller tappets and the plungers. For the Denso HP5D (and the closely related HP5), however, I’ve hit a wall – I can’t find a single clear illustration of its internal construction.

What I’m specifically looking for:

How rotary motion is converted into reciprocating plunger movement (cam ring with rollers vs. eccentric shaft)

How the roller tappet is prevented from rotating inside its bore

The second point is crucial for my comparison. In the CP4.2, one of the well-known catastrophic failure modes occurs when the roller tappet turns sideways, causing the roller to skid across the cam lobe rather than rolling – this destroys the pump and sends metal through the entire fuel system. I’m trying to understand exactly how Denso designed the HP5D to avoid this problem (or if it has a different weakness).

If anyone has access to a Denso service manual, an SAE paper, a training document, or even a personal photo of a disassembled pump that shows the cam ring, roller tappet, and anti-rotation feature, I’d be incredibly grateful. I’m also happy for any pointers on where to search – I’ve tried Denso’s public technical documents, Google Patents, and general image searches without success.

Thanks in advance for any help!

Hi everyone, I’m a mechanical engineering student currently writing a paper that compares the Bosch CP4.2 and Denso HP5D high-pressure common rail pumps.

I’ve easily found detailed diagrams, cross-sections, and even teardown photos for the Bosch CP4.2, which clearly show how the eccentric shaft drives the roller tappets and the plungers. For the Denso HP5D (and the closely related HP5), however, I’ve hit a wall – I can’t find a single clear illustration of its internal construction.

What I’m specifically looking for:

How rotary motion is converted into reciprocating plunger movement (cam ring with rollers vs. eccentric shaft)

How the roller tappet is prevented from rotating inside its bore

The second point is crucial for my comparison. In the CP4.2, one of the well-known catastrophic failure modes occurs when the roller tappet turns sideways, causing the roller to skid across the cam lobe rather than rolling – this destroys the pump and sends metal through the entire fuel system. I’m trying to understand exactly how Denso designed the HP5D to avoid this problem (or if it has a different weakness).

If anyone has access to a Denso service manual, an SAE paper, a training document, or even a personal photo of a disassembled pump that shows the cam ring, roller tappet, and anti-rotation feature, I’d be incredibly grateful. I’m also happy for any pointers on where to search – I’ve tried Denso’s public technical documents, Google Patents, and general image searches without success.

Thanks in advance for any help!

Hi everyone, I’m a mechanical engineering student currently writing a paper that compares the Bosch CP4.2 and Denso HP5D high-pressure common rail pumps.

I’ve easily found detailed diagrams, cross-sections, and even teardown photos for the Bosch CP4.2, which clearly show how the eccentric shaft drives the roller tappets and the plungers. For the Denso HP5D (and the closely related HP5), however, I’ve hit a wall – I can’t find a single clear illustration of its internal construction.

What I’m specifically looking for:

How rotary motion is converted into reciprocating plunger movement (cam ring with rollers vs. eccentric shaft)

How the roller tappet is prevented from rotating inside its bore

The second point is crucial for my comparison. In the CP4.2, one of the well-known catastrophic failure modes occurs when the roller tappet turns sideways, causing the roller to skid across the cam lobe rather than rolling – this destroys the pump and sends metal through the entire fuel system. I’m trying to understand exactly how Denso designed the HP5D to avoid this problem (or if it has a different weakness).

If anyone has access to a Denso service manual, an SAE paper, a training document, or even a personal photo of a disassembled pump that shows the cam ring, roller tappet, and anti-rotation feature, I’d be incredibly grateful. I’m also happy for any pointers on where to search – I’ve tried Denso’s public technical documents, Google Patents, and general image searches without success.

Thanks in advance for any help!